JP7356398B2 - pulley structure - Google Patents

Description

The present invention relates to a pulley structure equipped with a coil spring.

In an auxiliary drive unit that drives auxiliary equipment such as an alternator using the power of an automobile engine, a belt runs across a pulley connected to the drive shaft of the auxiliary equipment such as the alternator and a pulley connected to the engine crankshaft. engine torque is transmitted to the auxiliary equipment via this belt. In particular, the pulley connected to the drive shaft of the alternator, which has a large inertia compared to other auxiliary machines, has a pulley structure that can absorb rotational fluctuations of the crankshaft, as described in Patent Document 1, for example. used.

The pulley structure described in Patent Document 1 includes an outer rotating body, an inner rotating body that is provided inside the outer rotating body and is rotatable relative to the outer rotating body, and disposed between the two rotating bodies. It has a coiled spring.

In this pulley structure, rotational fluctuations of the crankshaft are transmitted to the outer rotating body via the belt, and when the two rotating bodies rotate relative to each other, torque is transmitted between the two rotating bodies via the coil spring. By twisting the coil spring in the circumferential direction, rotation fluctuations are absorbed (damping function). This makes it possible to suppress slips and tension fluctuations of the belt wound around the outer rotating body. Furthermore, torque is transmitted or interrupted between the outer rotor and the inner rotor by expanding or contracting the diameter of the coil spring (clutch function). Thereby, slipping of the belt can be reliably prevented.

In this way, the coil spring provided in this pulley structure has a damping function that absorbs rotational fluctuations of the crankshaft when transmitting torque between the outer rotor and the inner rotor, and a damping function that absorbs the rotational fluctuations of the crankshaft. It has a clutch function that transmits or interrupts torque to and from the body in one direction.

Japanese Patent Application Publication No. 2014-114947

Recently, driving support technology and self-driving technology for automobiles, etc. have progressed and become more widespread, and the number of sensors, cameras, electric motors, and their control devices mounted on vehicles has increased, resulting in greater power consumption than before. is consumed. For this reason, the amount of power generation required for the alternator will increase compared to before, and the alternator will become larger than before, and the mass of the rotating part of the alternator connected to the pulley structure via the drive shaft will be greater than before. It was decided to increase. As a result, the torque input to the outer rotating body (pulley) of the pulley structure (hereinafter referred to as input torque) increases based on the engine rotational fluctuation (maximum value) and the rotational inertial mass (inertial mass) of the alternator. became. Along with this, the load on the belt has also increased compared to before.

Due to the design of the pulley structure, the maximum input torque that can be normally allowed (hereinafter referred to as "allowable torque") is the surface of the coil spring (especially the inner periphery) where tensile force is applied when the coil spring is expanded in diameter. It is preferable that the bending stress (maximum value) generated on the coil spring be set to a level that can suppress the bending stress (maximum value) generated in the coil spring as low as possible and ensure sufficient durability against torsion of the coil spring. For this reason, the allowable torque is preferably set to a level of torsional torque (within a range in which the locking mechanism does not operate) that can avoid maximizing the radial expansion deformation of the coil spring in terms of safety.

Therefore, in order to withstand a larger input torque than the conventional one (for example, input torque increased by about 25% compared to the conventional one) with the conventional (Patent Document 1 etc.) pulley structure configuration (see FIG. 8), a coil spring is required. It is necessary to make the spring wire (strand wire) thicker.

However, simply making the spring wire (strand wire) of the coil spring thicker increases the spring constant (the ratio of torsion torque to the torsion angle of the coil spring, that is, the slope of the torque curve). Even if the wire is made thicker, the number of turns (effective number of turns) of the coil spring must be increased in order to increase the allowable torque while maintaining the spring constant at a predetermined level (the same level as before). (For example, if it used to be 7 turns, it must be increased to 9 turns).

In this case, the pulley structure naturally becomes larger in the direction of the rotation axis (and in the direction of the axis parallel to the engine crankshaft), and the alternator's overhang (the amount of protrusion from the bearing) becomes longer, which compensates for the bearing strength. Therefore, as a result of increasing the bearing size, the alternator becomes even larger. In other words, if the basic configuration of the conventional pulley structure (Patent Document 1, etc.) remains unchanged, it will increase in size in the direction of the rotation axis when dealing with excessive input torque. It was thought that there was a limit to increasing the permissible torque while securing mounting space and maintaining the spring constant at a predetermined level (comparable to the conventional level).

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pulley structure that can increase the degree of freedom in designing the spring constant and allowable torque without increasing the size in the direction of the rotation axis.

The pulley structure of the present invention includes a cylindrical outer rotating body around which a belt is wound,
an inner rotating body that is provided radially inside the outer rotating body and is rotatable relative to the outer rotating body about the same rotation axis as the outer rotating body;
a first coil spring provided between the outer rotary body and the inner rotary body and compressed in an axial direction along the rotation axis;
a second coil spring arranged radially in parallel with the first coil spring and compressed in an axial direction along the rotation axis;
When the first coil spring is torsionally deformed in the diameter expansion or diameter reduction direction, it engages with the outer rotary body and the inner rotary body, and generates torque between the outer rotary body and the inner rotary body. When the torque is transmitted and the torque is torsionally deformed in the opposite direction to the torque transmission, the engagement between the outer rotating body and the inner rotating body is released by sliding with the outer rotating body or the inner rotating body. Cutting off torque transmission between
The second coil spring has at least one axial end portion and the other end portion of the first coil spring that radially opposes the portion and engages with the outer rotating body. The first coil spring is formed to be connectable to one end side and the other end side in the axial direction, and is torsionally deformed in the same direction as the first coil spring when transmitting torque. It engages with the outer rotating body and the inner rotating body via a spring.

According to the above configuration, by arranging the second coil spring in parallel with the first coil spring in the radial direction and forming the two so that they can be connected, excessive input torque from the outer rotating body side can be transferred to the first coil spring. The damping function can be assigned to the second coil spring together with the coil spring, so that not only the first coil spring but also the second coil spring can perform the damping function. As a result, the pulley structure does not need to be enlarged in the direction of the rotational axis, and compared to a conventional pulley structure (with only one coil spring), the spring can be reduced to the same extent as when the effective number of turns of the coil spring is increased. The degree of freedom in designing the constant can be increased, and the allowable torque (maximum input torque) can be increased accordingly while maintaining the spring constant at a predetermined level (comparable to the conventional level).
In this manner, the damping function at the time of torque transmission can be effectively maintained even in response to excessive input torque from the outer rotating body side. Consequently, rotational fluctuations of the crankshaft can be sufficiently absorbed by the pulley structure.

Further, one aspect of the present invention is that in the above pulley structure,
The first coil spring is
a first end side region where the outer circumferential surface contacts one of the outer rotary body and the inner rotary body due to a self-elastic restoring force in a radially expanding direction when no external force is applied to the pulley structure; ,
a first other end side region where the inner peripheral surface contacts the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure on the other end side;
A first portion located between the first one end region and the first other end region and not in contact with either the outer rotating body or the inner rotating body when no external force is applied to the pulley structure. having a middle region;
When the first coil spring is twisted in a diametrically expanding direction due to relative rotation between the outer rotating body and the inner rotating body, the inner circumferential surface of at least a portion of the first other end side region is aligned with the outer rotating body. and configured to be separated from the other of the inner rotating bodies,
The second coil spring is
The first coil spring is provided between the first coil spring and the inner rotating body, one of the one end side and the other end side faces the part in the radial direction and engages with the outer rotating body. formed so as to be connectable to one of the one end side and the other end side of the first coil spring,
a second one-end region that contacts one of the outer rotating body and the inner rotating body on the one end side;
a second other end region where the inner peripheral surface contacts the other of the outer rotating body and the inner rotating body on the other end side when no external force is applied to the pulley structure;
Between the second one end region and the second other end region of the second coil spring, when no external force is applied to the pulley structure, the outer rotating body and the inner rotating body are a second middle area that does not contact any of the areas;
When the second coil spring is twisted in a radially expanding direction due to relative rotation between the outer rotor and the inner rotor, the inner portion of at least a portion of the second other end side region of the second coil spring is twisted. The peripheral surface is configured to be separated from the other of the outer rotating body and the inner rotating body.

According to the above configuration, (i) the two coil springs include a portion of the first coil spring that is engaged with the outer rotating body on either one of the axial end sides and the other end side; The second coil spring is formed so that only the portions of the second coil spring facing each other in the radial direction can be connected to each other.
(ii) When both of the two coil springs are twisted in the diameter expansion direction, at least the circumferential surface of the inner peripheral surface of the other end side region (the first other end side region, the second other end side region) One part of the direction is away from the other rotating body.
Further, (iii) the second coil spring is provided between the first coil spring and the inner rotating body so that the two coil springs are in an engaged state when both are twisted in the diametrically expanding direction. ing.
According to (i) and (ii) above, when the outer rotor and the inner rotor rotate relative to each other during torque transmission, the effective number of turns of the pulley structure increases compared to when the pulley structure is stopped. Therefore, the pulley structure of this embodiment has a configuration in which the effective number of turns of the first coil spring and the effective number of turns of the second coil spring are further increased when the outer rotor and the inner rotor rotate relative to each other. Therefore, the degree of freedom in designing the spring constant can be further increased.
According to (iii) above, the second coil spring is provided between the first coil spring and the outer rotating body so that the two coil springs are in an engaged state when both are twisted in the diameter reduction direction. Compared to the case, it is possible to suppress the pulley structure from unnecessarily increasing the size in the radial direction, and to minimize the increase in the size of the pulley structure in the radial direction.

Further, one aspect of the present invention is that in the above pulley structure,
The first coil spring is
a first end side region where the outer circumferential surface contacts one of the outer rotary body and the inner rotary body due to a self-elastic restoring force in a radially expanding direction when no external force is applied to the pulley structure; ,
a first other end side region where the inner peripheral surface contacts the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure on the other end side;
A first portion located between the first one end region and the first other end region and not in contact with either the outer rotating body or the inner rotating body when no external force is applied to the pulley structure. having a middle region;
When the first coil spring is twisted in a diametrically expanding direction due to relative rotation between the outer rotating body and the inner rotating body, the inner circumferential surface of at least a portion of the first other end side region is aligned with the outer rotating body. and configured to be separated from the other of the inner rotating bodies,
The second coil spring is
The first coil spring is provided between the first coil spring and the inner rotating body, one of the one end side and the other end side faces the part in the radial direction and engages with the outer rotating body. formed so as to be connectable to one of the one end side and the other end side of the first coil spring,
a second one-end region that contacts one of the outer rotating body and the inner rotating body on the one end side;
a second other end region on the other end side where the inner circumferential surface is separated from the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure;
Between the second one end region and the second other end region of the second coil spring, when no external force is applied to the pulley structure, the outer rotating body and the inner rotating body are and a second middle region that does not contact any of them.

According to the above configuration, (i) the two coil springs include a portion of the first coil spring that is engaged with the outer rotating body on either one of the axial end sides and the other end side; The second coil spring is formed so that only the portions of the second coil spring facing each other in the radial direction can be connected to each other.
Further, (ii) the inner peripheral surface of the second other end side region of the second coil spring is already separated from the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure. That is, the second other end side region of the second coil spring contacts the other of the outer rotating body and the inner rotating body only at the end face in the axial direction when no external force is applied to the pulley structure.
Therefore, in the pulley structure of this aspect, when the two rotating bodies rotate relative to each other during torque transmission, the effective number of turns of the second coil spring is further increased compared to the configuration of claim 2. The degree of freedom in designing the spring constant can be maximized.

It is a sectional view of a pulley structure of this embodiment. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 is a sectional view taken along line BB in FIG. 1. FIG. 2 is a sectional view taken along line CC in FIG. 1. FIG. (a) is a graph showing the relationship between the torsion angle of the coil spring and the torsion torque of the pulley structure shown in FIG. 1. FIG. (b) is a graph showing the relationship between the torsion angle and torsion torque of a coil spring in a conventional pulley structure. FIG. 2 is a perspective view for explaining details of an inner rotating body of the pulley structure shown in FIG. 1. FIG. It is an exploded view of the pulley structure of this embodiment. FIG. 2 is a cross-sectional view of a conventional pulley structure.

<Embodiment>
Hereinafter, a pulley structure 1 according to an embodiment of the present invention will be described.
The pulley structure 1 is installed on the drive shaft of an alternator in an automobile accessory drive system (not shown). The auxiliary drive system consists of a belt running between a drive pulley connected to the engine's crankshaft and a driven pulley that drives auxiliary machines such as an alternator. By being transmitted to the driven pulley, auxiliary equipment such as an alternator is driven. The rotational speed of the crankshaft fluctuates due to engine combustion, and the speed of the belt also fluctuates accordingly.

(Pulley structure 1)
As shown in FIGS. 1 to 4, the pulley structure 1 includes an outer rotating body 2, an inner rotating body 3, a first coil spring 4 (hereinafter simply referred to as "spring 4"), and a second coil spring 5 (hereinafter simply referred to as "spring 4"). (hereinafter simply referred to as "spring 5"), and an end cap 10. Hereinafter, the right side in FIG. 1 will be described as one end (rear) and the left side as the other end (front). The end cap 10 is arranged on the other end side of the outer rotating body 2 and the inner rotating body 3.

(Outer rotating body 2, inner rotating body 3)
Both the outer rotating body 2 and the inner rotating body 3 have a substantially cylindrical shape and have the same rotation axis. The rotation axes of the outer rotor 2 and the inner rotor 3 are the rotation axes of the pulley structure 1, and are hereinafter simply referred to as "rotation axes." Furthermore, the direction of the rotation axis is simply referred to as the "axial direction." The inner rotating body 3 is provided inside the outer rotating body 2 and is rotatable relative to the outer rotating body 2. A belt is wound around the outer peripheral surface of the outer rotating body 2.

The inner rotating body 3 has a cylinder main body 3a and an outer cylinder part 3b arranged outside the other end of the cylinder main body 3a. A drive shaft S such as an alternator is fitted into the cylinder body 3a. A support groove 3c is formed between the outer cylinder part 3b and the cylinder main body 3a. The inner peripheral surface of the outer cylinder part 3b and the outer peripheral surface of the cylinder main body 3a are connected via the groove bottom surface 3d of the support groove part 3c.

In the groove bottom surface 3d, in order to stabilize the postures of the springs 4 and 5 which are compressed in the axial direction, as shown in FIG. A first groove bottom surface 3d1 and a second groove bottom surface 3d2 having a spiral surface are formed in the portion where the groove bottom surface is formed.

As shown in FIG. 6, the second groove bottom surface 3d2 is formed so as to surround the cylinder body 3a with a spiral surface, and a second contact surface is formed at the step formed at the boundary where the spiral surface goes around. It has 3d4. In order to reliably transmit torque between the outer rotating body 2 and the inner rotating body 3, the second contact surface 3d4 has a circumferential end surface on the other end side (front side) of the spring 5 pressed in the positive direction. It faces the circumferential end face in the circumferential direction so as to obtain the same shape (see FIG. 3).

As shown in FIG. 6, the first groove bottom surface 3d1 is formed so as to surround the second groove bottom surface 3d2 one step below with a spiral surface, and a step is formed at the boundary where the spiral surface goes around. It has a first contact surface 3d3 (see FIG. 6). This first contact surface 3d3 is pressed in the positive direction by the circumferential end surface 4a on the other end side (front side) of the spring 4 in order to reliably transmit torque between the outer rotating body 2 and the inner rotating body 3. It faces the circumferential end surface 4a in the circumferential direction so that it can be rotated (see FIG. 2).

A rolling bearing 6 is interposed between the inner peripheral surface of one end of the outer rotating body 2 and the outer peripheral surface of the cylinder body 3a. Furthermore, a sliding bearing 7 is interposed between the inner circumferential surface of the other end of the outer rotating body 2 and the outer circumferential surface of the outer cylinder portion 3b. The outer rotary body 2 and the inner rotary body 3 are coupled by a rolling bearing 6 and a sliding bearing 7 so as to be relatively rotatable.

An annular thrust plate 8 is arranged between the outer rotating body 2 and the inner rotating body 3 and in front of the rolling bearing 6 (on the other end side). When assembling the pulley structure 1, the thrust plate 8 and the rolling bearing 6 are fitted onto the cylinder body 3a in this order.

A space 9 is formed between the outer rotating body 2 and the inner rotating body 3 and in front of the thrust plate 8. A spring 4 and a spring 5 are housed in the space 9. The space 9 is formed between the inner circumferential surface of the outer rotating body 2, the inner circumferential surface of the outer cylinder portion 3b, and the outer circumferential surface of the cylinder body 3a.

The inner diameter of the outer rotating body 2 decreases in two steps toward the rear. The inner circumferential surface of the outer rotating body 2 at the smallest inner diameter portion is referred to as a pressure contact surface 2a, and the inner circumferential surface of the outer rotating body 2 at the second smallest inner diameter portion is referred to as an annular surface 2b. The inner diameter of the outer rotating body 2 at the pressure contact surface 2a is smaller than the inner diameter of the outer cylinder portion 3b. The inner diameter of the outer rotating body 2 at the annular surface 2b is the same as or larger than the inner diameter of the outer cylinder portion 3b.

The outer peripheral surface of the inner rotating body 3 at the other end of the cylinder body 3a is referred to as a second contact surface 3e (see FIGS. 1 and 6). Further, the outer peripheral surface of the second groove bottom surface 3d2 is referred to as a first contact surface 3f (see FIGS. 1 and 6).

Further, on the inner circumferential surface of the outer cylindrical portion 3b, a protrusion that protrudes radially inward of the outer cylindrical portion 3b and faces the outer circumferential surface of the other end side region 4b (corresponding to the first other end side region) of the spring 4. 3g is provided. The protrusion 3g faces the second region 4b2 of the spring 4.

(First coil spring 4 and second coil spring 5)
In this embodiment, the allowable torque is set to a level of torsional torque that can avoid maximizing the diameter expansion deformation of the coil spring (activation of the locking mechanism) from a safety perspective, that is, a level slightly higher than the torsional torque at which the locking mechanism operates. The spring structure was designed by setting a relatively small torque level (the level of Tm1 in FIG. 5(a)).

(1) Maintain the spring constant k1 of the entire spring (two coil springs, spring 4 and spring 5) at a predetermined level (in this embodiment, the same level as the conventional spring constant k0: see FIG. 5(b)) Aiming to achieve this, the spring structure of each of the two coil springs (single body) of spring 4 and spring 5 was designed as follows.

(2) In addition to requirement (1), in order to raise the allowable torque (Tm1) in accordance with the increase in the inertial mass of the alternator (for example, about 25% compared to the conventional model), With the aim of effectively increasing the number of turns (effective number of turns) (in other words, effectively increasing the torsion angle of the entire spring), the spring structure of each (single unit) of the two coil springs, Spring 4 and Spring 5, is as follows. It was designed as such. In the following description, the cross section or cross-sectional shape of the spring wire refers to the cross section or cross-sectional shape along a direction passing through the rotation axis and parallel to the rotation axis.

(First coil spring 4)
The spring 4 is provided between the outer rotor 2 and the inner rotor 3 (specifically, the spring 4 is provided between the outer rotor 2 and the spring 5). The spring 4 is a torsion coil spring formed by spirally winding (coiling) a spring wire (spring wire material: oil-tempered spring wire (based on JIS G3560:1994)). The spring 4 is left-handed (counterclockwise from the other end to one end) (see FIG. 7). The spring 4 has a constant diameter over its entire length when it is not receiving any external force. The outer diameter of the spring 4 in a state where no external force is applied is larger than the inner diameter of the outer rotating body 2 at the pressure contact surface 2a. The spring 4 is housed in the space 9 with one end region 4c (corresponding to the first one end region) having a reduced diameter. The outer circumferential surface of the one end region 4c of the spring 4 is pressed against the pressure contact surface 2a by the self-elastic restoring force of the spring 4 in the diametrically expanding direction. The one end side region 4c is a region extending one or more turns from one end of the spring 4 (360° or more around the rotation axis).

In addition, when the pulley structure 1 is at rest (not receiving any external force), the outer circumferential surface of the one end side region 4c of the spring 4 is pressed against the pressure contact surface 2a by the self-elastic restoring force of the spring 4 in the diametrically expanding direction. In this state, the other end side region 4b of the spring 4 is in contact with the first contact surface 3f in a state where the diameter is slightly expanded. That is, when the pulley structure 1 is at rest, the inner peripheral surface of the other end side region 4b of the spring 4 is pressed against the first contact surface 3f. The other end side region 4b is a region extending one or more turns from the other end of the spring 4 (more than 360° around the rotation axis). When no external force is acting on the pulley structure 1, the spring 4 has a substantially constant diameter over its entire length.

The spring 4 is compressed in the axial direction when no external force is acting on the pulley structure 1 (that is, when the pulley structure 1 is stopped). In addition, a portion in the circumferential direction of the axial end face of the other end side region 4b of the spring 4 (approximately 1/4 circumference (approximately 90°) from the other end) is provided to stabilize the posture of the spring 4 that is compressed in the axial direction. Therefore, a first seat grinding surface 4e is formed (see FIG. 7). The first seat ground surface 4e is a plane that is perpendicular to the axial direction of the spring 4 and is formed by performing a grinding process. Similarly, in order to stabilize the posture of the spring 4 which is compressed in the axial direction, a portion in the circumferential direction of the axial end surface of the one end side region 4c of the spring 4 (approximately 1/4 circumference (approximately 90°) from the one end) is provided. A first seat grinding surface 4f is formed on.

The first ground surface 4e of the spring 4 is in contact with the first groove bottom surface 3d1 of the groove bottom surface 3d, and the first ground surface 4f of the spring 4 is in contact with the front surface of the thrust plate 8. The axial compression ratio of the spring 4 may be, for example, about 20%. The axial compression rate of the spring 4 is defined as the difference between the natural length of the spring 4 and the axial length of the spring 4 when no external force is applied to the pulley structure 1, and the natural length of the spring 4. This is the ratio of

As shown in FIG. 2, the circumferential end surface 4a on the other end side of the spring 4 faces the first contact surface 3d3 so as to be able to come into contact with it.

On the other hand, as shown in FIG. 4, a bent portion 4g that is bent inward in the radial direction is formed at one end of the spring 4. As shown in FIG. The bent portion 4g is formed in a straight line along the radial direction. The length of the bent portion 4g (the linear portion along the radial direction from the end point of the root rounded portion to the end face) is formed to be approximately the same as the radial length in the cross section of the spring wire of the spring 5. Thereby, the bent portion 4g can come into contact with (connect) a circumferential end surface 5g of the spring 5, which will be described later.

Further, the spring 4 is configured to have a lower spring constant than a conventional coil spring. Specifically, compared to a conventional coil spring, the spring 4 has the same number of turns (7 turns) and the same cross-sectional dimensions of the spring wire, but has a lower spring constant (the broken line in Fig. 5(a) slope), and the outer diameter is slightly larger (approximately 5%). In addition, with this configuration, the inner diameter of the pressure contact surface 2a (clutch engaging portion) of the outer rotating body 2 is also formed to be slightly larger (about 5%) than that of a conventional coil spring.

Further, as shown in FIG. 2, in the other end side region 4b of the spring 4, the vicinity of a position 90° away from the circumferential end surface 4a of the spring 4 around the rotation axis is more than the second region 4b2, the second region 4b2. The portion on the side of the circumferential end surface 4a is referred to as a first region 4b1, and the remaining portion is referred to as a third region 4b3. Further, in the region between the other end side region 4b and the one end side region 4c of the spring 4, that is, in a state where no external force is applied to the pulley structure 1, both the pressure contact surface 2a and the first contact surface 3f The non-contact area is defined as a free portion 4d (corresponding to the first middle area).

(Second coil spring 5)
The spring 5 is arranged in parallel with the spring 4 in the radial direction, and is provided between the spring 4 and the cylinder body 3a. Like spring 4, spring 5 is a torsion coil spring formed by spirally winding (coiling) a spring wire (spring wire material: oil tempered wire for springs (based on JIS G3560:1994)) (Fig. 7 reference). The spring 5 has a constant diameter over its entire length when not receiving any external force. The outer diameter of the spring 5 is smaller than the inner diameter of the spring 4 when it is not receiving any external force. The spring 5 is housed in the space 9 with one end region 5c (corresponding to the second one end region) neither expanded nor contracted in diameter. Therefore, the outer circumferential surface of the one end region 5c of the spring 5 does not interfere with (contact) the inner circumferential surface of the spring 4 (the one end region 5c of the spring 5 is compressed in the axial direction). , is in contact with the outer rotating body 2 via the thrust plate 8). The one end region 5c is a region extending one or more turns from one end of the spring 5 (360° or more around the rotation axis).

In addition, when the pulley structure 1 is at rest (no external force is applied to the pulley structure), the other end region 5b of the spring 5 (corresponding to the second other end region) has a slightly expanded diameter. In this state, it is in contact with the second contact surface 3e. That is, when the pulley structure 1 is at rest, the inner peripheral surface of the other end side region 5b of the spring 5 is pressed against the second contact surface 3e. The other end side region 5b is a region extending one or more turns from the other end of the spring 5 (more than 360 degrees around the rotation axis). When no external force is applied to the pulley structure 1, the spring 5 has a substantially constant diameter over its entire length.

The spring 5 is compressed in the axial direction when no external force is acting on the pulley structure 1 (that is, when the pulley structure 1 is stopped). In addition, a portion in the circumferential direction of the axial end surface of the other end side region 5b of the spring 5 (approximately 1/4 circumference (approximately 90°) from the other end) is provided to stabilize the posture of the spring 5 that is compressed in the axial direction. Therefore, a second seat grinding surface 5e is formed (see FIG. 7). The second ground surface 5e is a plane perpendicular to the axial direction of the spring 5, which is formed by performing a grinding process. Similarly, in order to stabilize the posture of the spring 5 which is compressed in the axial direction, a circumferential portion of the axial end surface of the one end side region 5c of the spring 5 (approximately 1/4 circumference (approximately 90°) from one end) is provided. A second seat grinding surface 5f is formed on.

The second ground surface 5e of the spring 5 is in contact with the second groove bottom surface 3d2 of the groove bottom surface 3d, and the second ground surface 5f of the spring 5 is in contact with the front surface of the thrust plate 8. The axial compression ratio of the spring 5 may be, for example, about 20%.

As shown in FIG. 3, the circumferential end surface 5a on the other end side of the spring 5 faces the second contact surface 3d4 so as to be able to come into contact with it.

On the other hand, the circumferential end surface 5g on one end side of the spring 5 is capable of contacting (connected to) the bent portion 4g of the spring 4, as shown in FIG.

Further, the spring 5 is configured to have a lower spring constant than the spring 4. Specifically, compared to spring 4, spring 5 has the same number of windings (7 turns) and a smaller outer diameter, but the spring constant is lower (dotted chain line in Fig. 5(a)). (tilt), the cross-sectional dimension of the spring wire is made significantly smaller.

Further, as shown in FIG. 1, in a region between the other end region 5b and one end region 5c of the spring 5, that is, in a state where no external force is applied to the pulley structure 1, the outer rotating body 2 and A region that does not come into contact with any of the inner rotating bodies 3 is defined as a free portion 5d (corresponding to a second middle region).

To summarize the first coil spring 4, the second coil spring 5, and the conventional coil spring (Patent Document 1), they are all made of oil-tempered spring wire (compliant with JIS G3560:1994). The number of turns is 7, and the winding direction is left-handed. Further, the outer diameter is "first coil spring 4 > conventional coil spring > second coil spring 5". Further, the cross-sectional dimension of the spring wire is "first coil spring 4≒conventional coil spring>second coil spring 5".

(Connection relationship between first coil spring 4 and second coil spring 5)
As described above, the bent portion 4g of the spring 4 and the circumferential end surface 5g of the spring 5 are configured to be able to contact (connect) (see FIG. 4).

Specifically, when the outer rotating body 2 and the spring 4 rotate relative to the inner rotating body 3 in the positive direction (arrow direction in FIG. 4) (when the outer rotating body 2 accelerates), one end side of the spring 4 The inner portion of the bent portion 4g (the portion on the positive direction side, the portion corresponding to the length of the bent portion 4g) and the circumferential end surface 5g on one end side of the spring 5 contact (connect).

Conversely, when the outer rotating body 2 and the spring 4 rotate relative to the inner rotating body 3 in the opposite direction (the direction opposite to the arrow direction in FIG. 4) (when the outer rotating body 2 decelerates), the spring 4 The inner part of the bent part 4g formed on one end side (the part on the positive side, the part corresponding to the length of the bent part 4g) is separated from the circumferential end surface 5g of the one end side of the spring 5 (the connection is not (can be in a released state).

(Thrust plate 8)
The thrust plate 8 has an annular plate shape (flat washer shape), is inserted into the cylinder body 3a, is located between the outer rotating body 2 and the inner rotating body 3, and is located in front of the rolling bearing 6 (at the other end). side). The thrust plate 8 is fixed to the outer rotating body 2 and rotates integrally with the outer rotating body 2. The front surface of the thrust plate 8 is in contact with the first ground surface 4f of the spring 4 and the second ground surface 5f of the spring 5. The thrust plate 8 is configured to slide in the circumferential direction on the first ground surface 4f of the spring 4 and the second ground surface 5f of the spring 5 when the outer rotating body 2 is decelerated (clutch disengaged state). Therefore, the thrust plate 8 (front end surface) is not formed with a spiral surface, but is formed with a flat surface perpendicular to the axial direction.

(Operation of pulley structure 1)
Next, the operation of the pulley structure 1 will be explained.

First, when the rotation speed of the outer rotor 2 becomes larger than the rotation speed of the inner rotor 3 (that is, when the outer rotor 2 accelerates, the outer rotor 2 and the spring 4 (when relative rotation in the positive direction with respect to) will be explained.

(1) The outer rotating body 2 rotates relative to the inner rotating body 3 in the positive direction (in the direction of the arrow in FIGS. 2 to 4). With the relative rotation of the outer rotating body 2, the one end side region 4c of the spring 4 moves together with the pressure contact surface 2a, and rotates relative to the inner rotating body 3. As a result, the spring 4 is torsionally deformed in the diametrically expanding direction (hereinafter referred to as "diametrically expanding deformation").

(2) The spring 5 is provided between the spring 4 and the inner rotating body 3, and the bent portion 4g of the spring 4 and the circumferential end surface 5g of the spring 5 can come into contact with each other. (Connectable), so in the case of (1) above, the spring 5 is also twisted in the diametrically expanding direction.

(3) The pressing force of the one end side region 4c of the spring 4 against the pressing surface 2a increases as the twist angle of the spring 4 in the diametrically expanding direction increases.

(4) The second region 4b2 in the other end region 4b of the spring 4 is most susceptible to torsional stress, and as the torsion angle in the diametrical direction of the spring 4 increases, it separates from the first contact surface 3f of the inner rotating body 3 . At this time, the first region 4b1 and the third region 4b3 are in pressure contact with the first contact surface 3f. Further, the other end side region 5b (inner circumferential surface) of the spring 5 is already separated from the outer circumferential surface of the cylinder body 3a even when no external force is applied to the pulley structure 1.

(5) At the same time as the second region 4b2 of the spring 4 separates from the first contact surface 3f, or when the torsion angle in the diametrical direction of the spring 4 becomes larger, the outer circumferential surface of the second region 4b2 becomes a protrusion. Contact with 3g. By the outer circumferential surface of the second region 4b2 coming into contact with the protrusion 3g, the diameter expansion deformation of the other end region 4b is restricted, and the torsional stress is dispersed to a portion of the spring 4 other than the other end region 4b. The torsional stress acting on the one end side region 4c increases. As a result, the difference in torsional stress acting on each part of the spring 4 is reduced, and strain energy can be absorbed by the entire spring 4, so that local fatigue failure of the spring 4 can be prevented.

(6) Furthermore, the pressing force of the third region 4b3 against the first contact surface 3f decreases as the twist angle of the spring 4 in the radially expanding direction increases. At approximately the same time that the second region 4b2 comes into contact with the protrusion 3g, or when the twist angle of the spring 4 in the diametrical direction becomes even larger, the contact force of the third region 4b3 against the first contact surface 3f becomes approximately zero. Become. At this time, the twist angle of the spring 4 in the diameter expansion direction is set to θ1 (for example, θ1=3°). When the twist angle in the diametrically expanding direction of the spring 4 exceeds θ1, the third region 4b3 undergoes diametrically expanding deformation and moves away from the first contact surface 3f.

(7) Further, the other end side region 5b (inner circumferential surface) of the spring 5 is originally separated from the outer circumferential surface of the cylinder body 3a (inner rotating body 3). Therefore, until the above twist angle (for example, θ1=3°) is reached, the other end region 5b of the spring 5 has a configuration in which the effective number of turns is increased compared to the other end region 4b of the spring 4. Therefore, the degree of freedom in designing the spring constant can be increased.

Furthermore, by adding the spring 5, the degree of freedom in designing the spring constant can be increased, and as mentioned above, the spring 5 is configured so that the spring constant of the spring 5 is lower than that of the spring 4. (dotted chain line in Fig. 5(a): between 0<θ<3°).

Further, as described above, the spring 4 is configured such that the spring constant of the spring 4 is smaller than the spring constant (k0) of a conventional coil spring (see FIG. 5(b)). As a result, the spring constant (k1) of the entire spring (two coil springs, spring 4 and spring 5) can be maintained at a predetermined level (in this embodiment, the same level as the conventional spring constant k0) (Fig. Solid line in 5(a): between 0<θ<3°).

(8) The spring 4 does not curve (bend) near the boundary between the third region 4b3 and the second region 4b2, and the other end region 4b is maintained in an arc shape. In other words, the other end side region 4b is maintained in a shape that allows it to easily slide on the projection 3g. Therefore, when the torsion angle in the diametrical direction of the spring 4 increases and the torsional stress acting on the other end region 4b increases, the other end region 4b of the spring 4 becomes the second region 4b2. The outer rotating body 2 slides in the circumferential direction (positive direction) with respect to the projection 3g and the first contact surface 3f against the pressure contact force against the projection 3g and against the pressure contact force against the first contact surface 3f of the first region 4b1. do. Along with this, the other end side region 5b of the spring 5 also moves in the circumferential direction (positive direction) of the outer rotating body 2. Then, the circumferential end surface 4a of the spring 4 presses the first contact surface 3d3, and the circumferential end surface 5a of the spring 5 presses the second contact surface 3d4. Torque can be reliably transmitted between. That is, the spring 5 engages with the outer rotating body 2 and the inner rotating body 3 via the spring 4 by torsionally deforming in the same direction as the spring 4 during torque transmission.

(9) Note that the torsion angle in the diameter expansion direction of the spring 4 is θ1 or more and θ2 (for example, θ2 = approximately 60°: The locking mechanism is When the working torsion angle θ2 is less than 60°, which is larger than the conventional 45°, the third region 4b3 is separated from the first contact surface 3f and comes into contact with the inner circumferential surface of the outer cylinder portion 3b. The second region 4b2 is in pressure contact with the projection 3g. Therefore, in this case, the effective number of turns of the spring 4 is larger and the spring constant (the slope of the straight line shown in FIG. 5(a)) is smaller than when the twist angle in the diameter expansion direction of the spring 4 is less than θ1. Furthermore, when the torsion angle in the diametrically expanding direction of the spring 4 reaches θ2, the outer circumferential surface of the free portion 4d of the spring 4 comes into contact with the annular surface 2b, thereby restricting further diametrically expanding deformation of the spring 4. A locking mechanism is activated in which the rotating body 2 and the inner rotating body 3 rotate integrally. This can prevent damage to the springs 4 and 5 due to their diameter expansion deformation.

In this embodiment, the allowable torque is set to a level of torsional torque that can avoid maximizing the radial expansion deformation of the spring 4 (activation of the locking mechanism), that is, higher than the torsional torque at which the locking mechanism operates. Although the spring structure was designed with the torque level set at a slightly lower level (the level of Tm1 in Figure 5(a)), by providing the above-mentioned locking mechanism, even more excessive torque could be input. can also protect the pulley structure 1.

At θ1 or more and less than θ2, by configuring the two coil springs, spring 4 and spring 5, as described above, the spring constant (k1) of the entire spring (the two coil springs, spring 4 and spring 5) can be set to a predetermined value. The spring constant can be maintained at the same level (in this embodiment, the same level as the conventional spring constant k0). Additionally, the allowable torque has been increased by about 25% from the conventional Tm0 to Tm1. The degree of bottom raising is equal to the torque increase corresponding to the increase (for example, about 25%) in the inertial mass of the alternator (solid line in FIG. 5(a): between 3°≦θ<60°).

In addition, in this embodiment, as the spring 4 expands in diameter, the spring 5 expands in diameter while substantially maintaining the radial clearance between the pulley structure 1 when no external force is applied to the pulley structure 1. Because of the deformation (inertial mass: second coil spring 5 < first coil spring 4), the spring 5 (outer circumferential surface) maintains a state in which it does not interfere with (contact) the spring 4 (inner circumferential surface). However, in order to reliably suppress problems (occurrence of abnormal noise and vibration) when the springs 4 and 5 interfere, a cylindrical cylinder is installed between the springs 4 (inner peripheral surface) and the springs 5 (outer peripheral surface). It is also possible to have a configuration in which a shaped elastic sleeve is attached. In this case, the "cylindrical elastic sleeve" is preferably made of, for example, synthetic rubber (for example, a rubber composition containing a rubber component such as urethane rubber, silicone rubber, or fluororubber).

Next, when the rotation speed of the outer rotor 2 becomes smaller than the rotation speed of the inner rotor 3 (that is, when the outer rotor 2 decelerates, the outer rotor 2 and the spring 4 3) will be explained.

In this case, the outer rotating body 2 rotates relative to the inner rotating body 3 in the opposite direction (the direction opposite to the arrow direction in FIGS. 2 to 4). With the relative rotation of the outer rotating body 2, the one end side region 4c of the spring 4 moves together with the pressure contact surface 2a, and rotates relative to the inner rotating body 3. As a result, the spring 4 is deformed in a diameter-reducing direction. When the torsion angle in the diameter reduction direction of the spring 4 is less than θ3 (for example, θ3=3°), the pressing force of the one end side region 4c against the pressing surface 2a is slightly lower than when the torsion angle is zero; One end side region 4c is in pressure contact with the pressure contact surface 2a. Further, the pressing force of the other end side region 4b against the first contact surface 3f increases slightly compared to the case where the twist angle is zero. When the torsion angle in the diameter reduction direction of the spring 4 is θ3 or more, the pressure contact force of the one end side region 4c with respect to the pressure contact surface 2a becomes approximately zero, and the one end side region 4c is to slide. Therefore, no torque is transmitted between the outer rotating body 2 and the inner rotating body 3 (see FIG. 5(a)).

Here, as shown in FIG. 5(a), the torsional torque of the spring 4 (hereinafter referred to as , "slip torque Ts") is preferably set to a torque that causes a slight diameter reduction deformation in the spring 4 (diameter reduction deformation with a torsion angle θ3 or more) rather than being set to zero. . Specifically, the slip torque Ts (absolute value) is preferably set to be 1 N·m or more and 10 N·m or less (for example, about 1 N·m).

With such torque characteristics, the clutch is disengaged only in specific driving patterns in which the rotation speed of the outer rotor 2 is smaller than the rotation speed of the inner rotor 3. It becomes like this. For example, when starting the engine, the driving pattern is such that the rotational speed of the outer rotating body 2 temporarily increases greatly and then decreases. Then, when the rotational speed of the outer rotary body 2 increases significantly, torque is transmitted from the outer rotary body 2 to the inner rotary body 3, and the rotational speed of the inner rotary body 3 increases. After that, when the rotation speed of the outer rotor 2 decreases, the rotation speed of the outer rotor 2 becomes slower than that of the inner rotor 3, and at this time, the clutch is disengaged (the outer rotor 2 and the inner rotor 3).

Here, unlike the case described above, a case will be considered in which the slip torque Ts is set to zero. In this case, the clutch is disengaged without being limited to a specific driving pattern (for example, when starting the engine). Therefore, the frequency at which the pressure contact surface 2a (clutch engagement portion) and the spring 4 slide (slip) increases. On the other hand, as described above, if the slip torque Ts is set to be applied only to a specific driving pattern, the frequency of sliding between the pressure contact surface 2a and the spring 4 is reduced, and the pressure contact surface 2a Wear of the part that slides with the spring 4 can be suppressed.

When the slip torque Ts (absolute value) is less than 1 N·m, the clutch is disengaged without being limited to a specific driving pattern (for example, when starting the engine). If the slip torque Ts (absolute value) exceeds 10 N·m, there is a possibility that the clutch may not be disengaged when starting the engine. If the clutch is not disengaged when the engine is started, it will not be possible to prevent the belt wound around the outer rotating body 2 from slipping, and in the worst case, the belt may come off the outer rotating body 2.

In this embodiment, when the spring 4 is housed between the outer rotor 2 and the inner rotor 3, the amount by which the diameter of the one end region 4c of the spring 4 is reduced (pressure force on the clutch engagement surface) is , by optimizing design values such as the amount by which the spring 4 is compressed in the axial direction (pressing force against the mating surface in the axial direction) and adjusting the sliding resistance between the spring 4 and the outer rotating body 2, the slip torque Ts can be reduced. is set to a torsion torque that causes the spring 4 to undergo a slight diameter reduction deformation.

In this way, the spring 4 is a coil spring type clutch, and functions as a one-way clutch that transmits or interrupts torque in one direction. When the outer rotating body 2 rotates relative to the inner rotating body 3 in the positive direction, the spring 4 engages with each of the outer rotating body 2 and the inner rotating body 3 to rotate the outer rotating body 2 and the inner rotating body 3. transmits torque between the On the other hand, when the outer rotating body 2 rotates relative to the inner rotating body 3 in the opposite direction, the spring 4 slides against the pressure contact surface 2a and generates a torque between the outer rotating body 2 and the inner rotating body 3. do not communicate.

Regarding the clutch function, the spring 5 merely undergoes a slight diameter reduction deformation in accordance with the slight diameter reduction deformation of the spring 4, and does not have a clutch function.

As described above, by arranging the second coil spring 5 in parallel with the first coil spring 4 in the radial direction and forming the two so that they can be connected in the above manner, excessive input from the outer rotating body 2 can be prevented. The second coil spring 5 is responsible for the torque together with the first coil spring 4, and not only the first coil spring 4 but also the second coil spring 5 is able to perform the damping function. As a result, the number of turns (effective number of turns) of the coil spring can be increased compared to a conventional pulley structure (when only one coil spring is provided) without increasing the size of the pulley structure 1 in the direction of the rotation axis. (for example, from 7 turns to 9 turns), the degree of freedom in designing the spring constant can be increased to the same extent as when changing the spring constant from 7 turns to 9 turns. It has been found that the allowable torque can be increased while maintaining the constant K1 (corresponding to the increase in the inertial mass of the alternator, it is increased by about 25% from the conventional Tm0 to Tm1).
In this way, the damping function during torque transmission can be effectively maintained even in response to excessive input torque from the outer rotating body 2 side. Consequently, rotational fluctuations of the crankshaft can be sufficiently absorbed by the pulley structure 1.

According to the above configuration, (i) the two coil springs, the spring 4 and the spring 5, are radially opposed to the one end region 4c of the spring 4 that engages with the outer rotating body 2, and the one end region 4c of the spring 4; However, the springs 5 are formed so that they can be connected only at one end side regions 5c.
(ii) When the two coil springs, spring 4 and spring 5, are twisted in the diametrically expanding direction, at least the inner circumferential surface of the other end side region 4b and the other end side region 5b, in the circumferential direction. One part is separated from the other rotating body.
(iii) The spring 5 is provided between the spring 4 and the inner rotating body 3 so that the two coil springs, the spring 4 and the spring 5, are in an engaged state when both are twisted in the diametrically expanding direction. It is being
Due to (i) and (ii) above, when the outer rotating body 2 and the inner rotating body 3 rotate relative to each other during torque transmission, the effective number of turns of the pulley structure 1 increases compared to when the pulley structure 1 is stopped. do. Therefore, in the pulley structure 1 of this embodiment, when the outer rotating body 2 and the inner rotating body 3 rotate relative to each other, the effective number of turns of the spring 4 and the effective number of turns of the spring 5 are further increased. The degree of freedom in designing the spring constant can be further increased.
According to (iii) above, the spring 5 is provided between the spring 4 and the outer rotating body 2 so that the two coil springs, the spring 4 and the spring 5, are in an engaged state when both are twisted in the diameter reduction direction. Compared to the case where the pulley structure 1 is expanded in the radial direction, it is possible to suppress the pulley structure 1 from unnecessarily increasing the size in the radial direction, and to minimize the increase in the size of the pulley structure 1 in the radial direction.

Further, the inner peripheral surface of the other end side region 5b of the spring 5 is already separated from the inner rotating body 3 when no external force is applied to the pulley structure 1. In other words, the other end region 5b of the spring 5 contacts the inner rotating body 3 only at the axial end surface (circumferential end surface 5a) when no external force is applied to the pulley structure 1.
Therefore, the pulley structure 1 of the present embodiment is configured to further increase the effective number of turns of the spring 5 when the outer rotating body 2 and the inner rotating body 3 rotate relative to each other during torque transmission. , the degree of freedom in designing the spring constant can be maximized.

(Other embodiments)
In the embodiment described above, by providing the second coil spring 5 between the first coil spring 4 and the cylindrical body 3a, the two coil springs, the spring 4 and the spring 5, are torsionally deformed in the diametrical direction. Although the configuration is such that the outer circumferential surface of the spring 4 is sometimes in a disengaged state (the outer circumferential surface of the spring 4 is in a disengaged state with the pressure contact surface 2a (clutch engaging portion) of the outer rotating body 2), is not limited. That is, the second coil spring 5 is located on the side that does not interfere with the clutch function of the first coil spring 4, in other words, the portion of the outer rotor 2 or the inner rotor 3 that slides with the first coil spring 4 ( It is sufficient if it is provided on the side that does not interfere with the clutch engaging portion). For example, the second coil spring 5 may be provided between the first coil spring 4 and the outer rotating body 2. In this case, the configuration is such that when the two coil springs, spring 4 and spring 5, are both torsionally deformed in the diametrically expanding direction, the engagement is released (the inner circumferential surface of the first coil spring 4 is 3a (clutch engagement portion) and a configuration in which it is in a disengaged state).

Moreover, the connection point between the spring 4 and the spring 5 is one place (the one end region 4c of the spring 4 and the one end region 5c of the spring 5, or the other end region 4b of the spring 4 and the one end region 5c of the spring 5). This is not limited to the parts of the other end side region 5b). That is, at least one portion of the one end side region 5c and the other end side region 5b of the spring 5, and the one end side region 4c of the spring 4 that radially opposes this portion and engages with the outer rotating body 2. and one part of the other end side area 4b are formed so that the two coil springs of spring 4 and spring 5 can be connected to each other at two places (one end side area 4c of spring 4 and The first end region 5c of the spring 5 may be the other end region 4b of the spring 5, and the other end region 4b of the spring 5 may be the other end region 5b of the spring 5. Further, the connection is not limited to the ends, but may be between parts other than the ends.

In addition, when the outer rotating body 2 and the inner rotating body 3 are twisted in the diametrically expanding direction due to relative rotation, the inner circumferential surface of the other end region 4b of the spring 4 and the inner circumferential surface of the other end region 5b of the spring 5 This may be configured such that any portion in the circumferential direction does not separate from the other of the outer rotating body and the inner rotating body.

Further, the connection relationship between the two coil springs, spring 4 and spring 5, is such that the circumferential end surface 5g on one end side of the spring 5 can come into contact with the bent portion 4g of the spring 4, as in the above embodiment. The present invention is not limited to the embodiment shown in FIG. 4. For example, the parts other than the one end region 4c of the spring 4 and the one end region 5c of the spring 5 may be configured to be able to contact (connect) with each other (not shown). Further, for example, a key (a cylindrical pin embedded so as to protrude radially outward) may be provided in the one end region 5c of the spring 5, and a keyway (a key groove provided radially inward) may be provided in the one end region 4c of the spring 4. A hole) may be provided, and the one end region 4c of the spring 4 and the one end region 5c of the spring 5 may be fixed to each other in the circumferential direction by engagement between the key and the keyway.

1 Pulley structure 2 Outer rotating body 3 Inner rotating body 4 First coil spring 5 Second coil spring 6 Rolling bearing 7 Sliding bearing 8 Thrust plate 9 Space 10 End cap

Claims (3)

a cylindrical outer rotating body around which the belt is wrapped;
an inner rotating body that is provided radially inside the outer rotating body and is rotatable relative to the outer rotating body about the same rotation axis as the outer rotating body;
a first coil spring provided between the outer rotary body and the inner rotary body and compressed in an axial direction along the rotation axis;
a second coil spring arranged radially in parallel with the first coil spring and compressed in an axial direction along the rotation axis;
When the first coil spring is torsionally deformed in the diameter expansion or diameter reduction direction, it engages with the outer rotary body and the inner rotary body, and generates torque between the outer rotary body and the inner rotary body. When the torque is transmitted and the torque is torsionally deformed in the opposite direction to the torque transmission, the engagement between the outer rotating body and the inner rotating body is released by sliding with the outer rotating body or the inner rotating body. Cutting off torque transmission between
The second coil spring has one end side and the other end side in the axial direction that are radially opposed to the first end side and the other end side of the first coil spring that engages with the outer rotating body. It is formed so that it can be connected at one point on one end side and the other end side in the axial direction, and when torque is transmitted, the first coil spring is torsionally deformed in the same direction as the first coil spring. A pulley structure, wherein the pulley structure engages with the outer rotating body and the inner rotating body via a coil spring. The first coil spring is
a first end side region where the outer circumferential surface contacts one of the outer rotary body and the inner rotary body due to a self-elastic restoring force in a radially expanding direction when no external force is applied to the pulley structure; ,
a first other end side region where the inner peripheral surface contacts the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure on the other end side;
A first portion located between the first one end region and the first other end region and not in contact with either the outer rotating body or the inner rotating body when no external force is applied to the pulley structure. having a middle region;
When the first coil spring is twisted in a diametrically expanding direction due to relative rotation between the outer rotating body and the inner rotating body, the inner circumferential surface of at least a portion of the first other end side region is aligned with the outer rotating body. and configured to be separated from the other of the inner rotating bodies,
The second coil spring is
The first coil spring is provided between the first coil spring and the inner rotating body, one of the one end side and the other end side faces the part in the radial direction and engages with the outer rotating body. formed so as to be connectable to one of the one end side and the other end side of the first coil spring,
a second one-end region that contacts one of the outer rotating body and the inner rotating body on the one end side;
a second other end region where the inner peripheral surface contacts the other of the outer rotating body and the inner rotating body on the other end side when no external force is applied to the pulley structure;
Between the second one end region and the second other end region of the second coil spring, when no external force is applied to the pulley structure, the outer rotating body and the inner rotating body are a second middle area that does not contact any of the areas;
When the second coil spring is twisted in a radially expanding direction due to relative rotation between the outer rotor and the inner rotor, the inner portion of at least a portion of the second other end side region of the second coil spring is twisted. The pulley structure according to claim 1, wherein the peripheral surface is separated from the other of the outer rotating body and the inner rotating body. The first coil spring is
a first end side region where the outer circumferential surface contacts one of the outer rotary body and the inner rotary body due to a self-elastic restoring force in a radially expanding direction when no external force is applied to the pulley structure; ,
a first other end side region where the inner peripheral surface contacts the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure on the other end side;
A first portion located between the first one end region and the first other end region and not in contact with either the outer rotating body or the inner rotating body when no external force is applied to the pulley structure. having a middle region;
When the first coil spring is twisted in a diametrically expanding direction due to relative rotation between the outer rotating body and the inner rotating body, the inner circumferential surface of at least a portion of the first other end side region is aligned with the outer rotating body. and configured to be separated from the other of the inner rotating bodies,
The second coil spring is
The first coil spring is provided between the first coil spring and the inner rotating body, one of the one end side and the other end side faces the part in the radial direction and engages with the outer rotating body. formed so as to be connectable to one of the one end side and the other end side of the first coil spring,
a second one-end region that contacts one of the outer rotating body and the inner rotating body on the one end side;
a second other end region on the other end side where the inner circumferential surface is separated from the other of the outer rotating body and the inner rotating body when no external force is applied to the pulley structure;
Between the second one end region and the second other end region of the second coil spring, when no external force is applied to the pulley structure, the outer rotating body and the inner rotating body are The pulley structure according to claim 1, further comprising a second middle region that does not contact any of the second middle regions.

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