JP5072051B2 - Pulley structure - Google Patents

Description

  The present invention relates to a pulley structure between two rotating bodies capable of relative rotation, and more specifically, relates to a pulley structure in which an elastic member connects the two rotating bodies to absorb rotational fluctuations.

An alternator provided in the automobile for power generation is connected to and driven by a crankshaft provided in the engine. However, due to the characteristics of the internal combustion engine, the crankshaft connected to the crankshaft is subject to rotational fluctuations in which acceleration and deceleration are frequently repeated in the rotational direction.
Here, the generator shaft of the alternator has a large moment of inertia. Therefore, in the configuration in which the power generation shaft and the crankshaft are connected using a pulley and a belt to transmit power, slippage occurs between the pulley and the belt each time the belt speed (crankshaft rotation speed) changes. A belt squeal is induced.
Furthermore, when the rotational fluctuation of the crankshaft is transmitted to the power generation shaft, there is a problem that the power generation mechanism of the alternator deteriorates and the power generation efficiency decreases.

  Therefore, as a pulley suitable for the rotation transmission system, that is, a pulley that absorbs the rotational fluctuation of the crankshaft, for example, a pulley with a damper including an elastic member and a viscous fluid between two relatively rotatable rotors ( Patent Document 1) and a pulley in which only an elastic member is provided between the two rotating bodies are mentioned.

Patent Document 1 shows an example of a pulley structure that absorbs rotational fluctuation of a crankshaft using an elastic member and a special viscous fluid. This pulley structure has a rubber elastic member between the first rotating body and the second rotating body that can rotate relative to each other, and viscosity increases with an increase in shearing force that occurs when rotational fluctuation occurs. And a viscous fluid having properties.
With this configuration, even if a torque that can generate a shearing stress exceeding the elastic limit of the elastic member acts on the pulley structure, the relative angle between the first rotating body and the second rotating body is increased by increasing the viscosity of the viscous fluid. The displacement is suppressed and the elastic member is prevented from being damaged by yielding or breaking.

On the other hand, a pulley structure in which only an elastic member is provided between the first rotating body and the second rotating body can be given as an example. The elastic member is a coil spring, and its end portion is fitted and fixed in an arc-shaped accommodation groove provided in the first rotating body and the second rotating body, and its end is bent and locked to each rotating body. Has been. A constant gap is provided between the coil spring and the arc-shaped receiving groove in the receiving groove in a region where the end of the coil spring is released from the fitting and fixing by the arc-shaped receiving groove. It has been.
As described above, in the configuration in which only the elastic member is used to absorb the rotation fluctuation, a larger relative angular displacement can be secured as compared with Patent Document 1, so that the tension fluctuation of the belt wound around the pulley can be reduced. Can be reduced. Thereby, there is an effect that belt squeal is suppressed and the durability of the belt is improved.

By the way, Patent Document 2 (corresponding US publication; US Pat. No. 5,139,463) discloses a pulley used in an alternator in a serpentine drive mechanism for an automobile.
The pulley includes a hub structure that rotates together with the armature assembly, and an AC generator pulley that is mounted on the hub structure, and a coil spring is provided at each end between the hub structure and the AC generator pulley. The structure is such that the driven rotational movement of the AC generator pulley by the meander belt is transmitted to the hub structure, and the relative elastic rotational movement in the opposite direction is also possible with respect to the AC generator pulley. ing. The end of the coil spring is bent outward in the radial direction, and the end is accommodated in a notch provided in the hub structure and the AC generator pulley.

JP-A-8-240246 Japanese Patent No. 3268007

However, in the configuration of Patent Document 1, since an annular rubber is employed as an elastic member provided between the first rotating body and the second rotating body, generally the amount of elastic deformation within the elastic limit, that is, The relative angular displacement allowed between the two rotating bodies is not sufficiently ensured.
Furthermore, when the crankshaft and the alternator with the rotational fluctuation are coupled using the damper-equipped pulley provided with the elastic member as shown in Patent Document 1, the fluctuation torque due to the rotational fluctuation is not easily transmitted to the alternator. On the other hand, since the belt is likely to resonate due to fluctuations in tension, new noise is generated and the durability of the belt is adversely affected.

On the other hand, in a pulley structure that uses a coil spring as an elastic member and does not have a damper, problems such as resonance of the belt, noise accompanying it, and deterioration in durability of the belt as shown in Patent Document 1 do not occur. The relative angular displacement between the generator and the generator shaft increases, and the coil spring may be damaged for the following reasons.
That is, a clear corner portion (simple step) is formed at the boundary between the coil spring and the region fitted and fixed to the rotating body and the region where the gap is provided. Whenever elastic deformation occurs, stress concentration occurs in the vicinity of the corner portion. Therefore, this pulley structure has a possibility that the boundary portion of the coil spring may be fatigued and destroyed by a local repeated stress generated every time the crankshaft rotates.

  By the way, in the structure of patent document 2, stress concentration is easy to generate | occur | produce in the edge part bent to the radial direction outer side, and there existed a problem that a coil spring will be damaged in a comparatively short period.

  The present invention has been made in view of the above-mentioned various points, and its main purpose is to ensure the resonance of the belt, the noise, the durability, and the relative angular displacement between the pulley and the generator shaft of the alternator. A coil spring is employed as a member that gently absorbs the relative angular displacement, and an object of the present invention is to provide a pulley structure in which the coil spring does not cause fatigue failure.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

(Claim 1)
A first rotating body capable of winding a belt; a second rotating body rotatable relative to the first rotating body inside the first rotating body; the first rotating body and the second rotating body; A pulley housing comprising a spring housing chamber formed between and a coil spring housed in the spring housing chamber, one end fixed to the first rotating body and the other end fixed to the second rotating body The at least one of the first rotating body and the second rotating body includes an arc-shaped receiving groove that receives an end of the coil spring, and the receiving groove is covered by the coil spring. The press-fitting part has a press-fitting part that is press-fitted and fixed , and irregularities arranged in the circumferential direction of the receiving groove are formed on the side wall of the press-fitting part. An unevenness that engages with the unevenness of the press-fitting portion is formed. And are the are supported in contact with the press-fit portion is at least three or more with respect to the side walls of the press-fit portion.
With the above configuration, by using a coil spring as an elastic member as a means for gently absorbing the crankshaft rotation fluctuation, a larger relative angular displacement than when rubber or the like is used for the elastic member can be allowed and secured. , Easy to absorb rotational fluctuation.
Along with this, belt tension fluctuations can be suppressed, so that belt resonance can be suppressed, whereby the generation of new noise in the belt can be prevented and the durability of the belt can also be improved.
Moreover, since the latching force with respect to the edge part of the said coil spring of the said accommodation groove can be enlarged, it can prevent that the said edge part slides with respect to the said accommodation groove, or is extracted from the said accommodation groove. Further, since the end of the coil spring is supported at three or more points with respect to the housing groove, the posture of the coil spring can be stabilized.

(Claim 2 )
It is preferable that the press-fitting part or the pressed-in part has a region where the unevenness is provided and a region where the unevenness is not provided.

(Claim 3 )
The irregularities are preferably formed by serration or knurling.
Thereby, the mechanical latching of unevenness | corrugation can be performed reliably.

(Claim 4 )
A first rotating body capable of winding a belt; a second rotating body rotatable relative to the first rotating body inside the first rotating body; the first rotating body and the second rotating body; A pulley housing comprising a spring housing chamber formed between and a coil spring housed in the spring housing chamber, one end fixed to the first rotating body and the other end fixed to the second rotating body The at least one of the first rotating body and the second rotating body includes an arc-shaped receiving groove that receives an end of the coil spring, and the receiving groove is covered by the coil spring. The press-fit portion has a press-fit portion that is press-fitted and fixed, and at least two or more wide portions that contact the side wall of the press-fit portion are formed in the press-fit portion.
With this configuration, the bending deformation load of the coil spring is shared and supported by at least four of the abutting portions, so that stress concentration on the coil spring at the time of rotational fluctuation can be prevented more reliably.

(Claim 5 )
The wide portion is preferably formed by pressing a peripheral wall of the coil spring.
Thereby, the said wide part can be formed at low cost. Moreover, since the magnitude | size (width | variety) of the said wide part can be freely changed only by adjusting press amount, the cost increase accompanying a design change can be suppressed, for example.

(Claim 6 )
The press-fitting allowance of the press-fitted part to the press-fitted part is preferably 0.1 mm or more and 0.5 mm or less. In addition, when there are a plurality of contact portions of the meandering portion or the wide portion with respect to the receiving groove, it is sufficient that at least one of them meets the above condition.
By setting the press-fitting allowance to be 0.1 mm or more as described above, the engaging force of the receiving groove with respect to the end portion of the coil spring can cause the end portion to slide with respect to the receiving groove, or the receiving groove. It can be secured enough not to be pulled out from.
On the other hand, when the press-fitting allowance is 0.5 mm or less, the assemblability of the pulley structure can be improved.

(Claim 7 )
It is preferable that a press-fitting allowance of the press-fitted part with respect to the press-fitted part becomes smaller as the distance from the terminal end of the coil spring is increased.
According to this, at the end of the coil spring, the generated stress becomes larger as it is away from the end, in other words, the stress unevenness problem that the generated stress at the farthest from the end is maximized at the end is solved. As a result, the life of the coil spring can be extended.

(Claim 8 )
The press-fitting allowance is preferably less than 0.1 mm on the side far from the end of the coil spring and 0.1 mm or more on the near side. Thereby, said effect is show | played more reliably.

(Claim 9 )
The groove width of the receiving groove is preferably constant. Thereby, since the process of the said accommodation groove can be made easy, an inexpensive pulley structure can be provided.

(Claim 10 )
It is preferable that an end winding portion further extending along the receiving groove and having a surface perpendicular to the coil axis is formed at the end of the coil spring.
Thereby, since the auxiliary winding part of the coil spring and the bottom surface of the housing groove to which the auxiliary winding part is press-fitted and fixed are brought into surface contact with each other, it is possible to prevent the shake of the coil shaft center of the coil spring, Assembly workability is improved.

(Claim 11 )
The coil spring is preferably a rectangular coil spring having a rectangular cross section.
With the above configuration, the following effects can be obtained by comparing a coil spring having a circular cross section with the rectangular coil spring. That is, for the same relative angular displacement, the same number of turns, and the same spring constant, the maximum tensile (compressive) stress generated in the latter coil spring can be reduced to, for example, about 70%, while the same relative angle. If the maximum tensile (compression) stress generated in the displacement is the same and the spring constant is the same, the latter required number of turns is, for example, 70%.

(Claim 12 )
At least one first protrusion is provided on the inner peripheral wall of the first rotating body, and at least one second protrusion that can contact the first protrusion is provided on the outer peripheral wall of the second rotating body; When the first rotating body and the second rotating body relatively rotate to a predetermined angle, it is preferable that the relative rotation exceeding the angle is restricted.
With the above configuration, an upper limit is provided for the deformation of the coil spring. In other words, since an upper limit is provided for the stress of the coil spring, fatigue or breakage of the coil spring can be suppressed without excessive force acting on the coil spring.

(Claim 13 )
It is preferable that a friction member is interposed between the first rotating body and the second rotating body.
As a result, the relative rotational motion between the first rotating body and the second rotating body is attenuated, and deformation of the coil spring is also suppressed. As a result, a long-life pulley structure can be provided.

(Claim 14 )
The friction member is interposed between one of the first rotating body and the second rotating body and a pressure plate slidably provided on the other, and the pressure plate includes the friction member. It is preferable that the urging force is applied by an appropriate urging means in a direction to be pressed against the one side.
Thereby, a large damping force can be applied to the relative rotational movement of the first rotating body with respect to the second rotating body.

(Claim 15 )
It is preferable that a cylindrical spring holder is provided on at least one of the outer peripheral side and the inner peripheral side of the coil spring.
Thereby, since the deformation amount in the diameter expansion (reduction) direction of the coil spring does not become excessive, damage to the coil spring can be prevented.
In addition, since the spring holder is provided, even if the coil spring is expanded (or reduced in diameter), it does not directly rub against the first rotating body (or the second rotating body). Damage to the coil spring 7 can be suppressed. This is particularly useful when it is desired to make the space between the coil spring and the first rotating body (or the second rotating body) as narrow as possible, for example, as shown in FIG.

Sectional drawing of the pulley structure which concerns on 1st Embodiment of this invention. The AA arrow directional view of FIG. FIG. 9 is a partial schematic view showing a modification of the pulley structure according to the first embodiment of the present invention, similar to FIG. 2. Sectional drawing of the pulley structure which concerns on 2nd Embodiment of this invention. The BB cross-sectional arrow figure in FIG. Sectional drawing which shows the modification of 2nd Embodiment. It is sectional drawing of the pulley structure which concerns on 3rd Embodiment of this invention, Comprising: The figure similar to FIG. FIG. 9 is a modified example of the third embodiment and is similar to FIG. 7. It is sectional drawing of the pulley structure which concerns on 4th Embodiment of this invention, Comprising: The figure similar to FIG. Sectional drawing of the pulley structure which concerns on 5th Embodiment of this invention. FIG. 11 is an EE cross-sectional arrow view in FIG. 10.

  Hereinafter, a pulley structure according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a pulley structure according to a first embodiment of the present invention, and FIG. 2 is a view taken along the line AA in FIG.

  Here, an embodiment in which the pulley structure according to the present invention is installed on a power generation shaft of an alternator of an automobile will be described.

  A pulley structure 1 shown in FIG. 1 is installed on a generator shaft (not shown) of an automobile alternator, and rotates when engine power is transmitted through a belt (not shown). Is done. The pulley structure 1 includes a first rotating body 2 on the outer periphery thereof, and a pulley body 2 a on which the belt can be wound is provided on the outer peripheral surface of the first rotating body 2. The first rotating body 2 is formed in a substantially cylindrical shape.

  A bearing 4 is disposed on the inner circumference on the one axial end side of the first rotating body 2, and a bearing 5 is disposed on the inner circumference on the other axial end side. The bearing 4 and the bearing 5 support the second rotating body 3 so as to be rotatable relative to the first rotating body 2, and the second rotating body 3 is accommodated in the first rotating body 2. .

  Stop members 31, 32 for fixing the bearing 4 and the bearing 5 so as not to come off are fitted on the outer periphery of the second rotating body 3, respectively. In addition, the shaft hole 3a of the second rotating body 3 is formed so that a generator shaft (not shown) of the alternator can be fixed.

  In the present embodiment, ball bearings are used as the bearing 4 and the bearing 5, but the configuration is not limited to this, and the configuration may be simplified by employing, for example, dry metal.

A spring accommodating chamber 6 is formed by the first rotating body 2 and the second rotating body 3 and the bearings 4 and 5.
An arc-shaped first accommodation groove 2 b is formed in the inner wall on one axial end side of the first rotating body 2, and is in the spring accommodating chamber 6 on the outer peripheral surface of the second rotating body 3. A wall constituting the arc-shaped second housing groove 3b is projected from a position corresponding to the first housing groove 2b in the axial direction.

  A coil spring 7 (square coil spring) having a rectangular cross section is housed in the spring housing chamber 6 and between the first housing groove 2b and the second housing groove 3b. .

  The coil spring 7 is disposed inside the spring accommodating chamber 6 so that the axis of rotation of the pulley structure 1 coincides with the axis, and one end is disposed on the inner wall of the first accommodating groove 2b and the other end is accommodated in the second. The inner wall of the groove 3b is press-fitted and fixed. Thereby, the first rotating body 2 and the second rotating body 3 are elastically connected via the coil spring 7.

  Hereinafter, the first housing groove 2b and the second housing groove 3b will be described in detail.

(Outline of receiving groove)
The first housing groove 2b is formed so as to surround the three sides of the spring wire of the coil spring 7 and to open the spring housing chamber 6 side. Similarly, the second housing groove 3b is formed so as to surround the three sides of the spring wire of the coil spring 7 and to open the spring housing chamber 6 side. Both end portions of the coil spring 7 are accommodated in the first accommodation groove 2b and the second accommodation groove 3b, respectively.

(Fitting fit by press fitting)
As shown in FIG. 2, in the storage groove 2b (3b), a wobbling meandering surface 2e is formed on the side wall of the press-fit portion 11 into which the press-fit portion 7a of the terminal end 7b of the coil spring 7 is press-fitted. Has been. Then, the press-fit portion 7a of the coil spring 7 is press-fitted and fitted into the press-fit portion 11 so that both are firmly fixed.
With this configuration, the coil spring 7 and the press-fit portion 11 are elastically deformed alternately toward the inner peripheral side and the outer peripheral side along the circumferential direction of the first receiving groove 2b, and the restoring force generated thereby is also the same on the inner peripheral side and It will act alternately on the outer peripheral side. Therefore, the frictional force between the coil spring 7 and the press-fit portion 11 can be greatly improved.
In addition, as shown in FIG. 2, it is preferable that the unevenness | corrugation which comprises the said meandering surface 2e formed in the said both wall surface of the said press-fit part 11 is formed so that each may correspond mutually in radial direction. As a result, the end 7b of the coil spring 7 is also elastically deformed in a meandering manner, and both side surfaces of the meandering coil spring 7 and the meandering surface are finely engaged with each other, so that the coil spring 7 and the press-fit portion 11 are engaged. The frictional force (locking fixing force) can be further improved.

(Wall surface of the receiving groove)
In FIG. 1, the outer peripheral side wall surface of the second accommodation groove 3b may be formed thin. By thinning the wall surface of the housing groove in this manner, the press-fit portion 7a of the coil spring 7 can be easily press-fitted and fitted into the corresponding housing groove. Furthermore, when the pulley structure 1 is operated, the coil spring 7 can be elastically deformed even in the pressed-in portion 7a, so that uneven deformation that causes stress concentration can be suppressed. In other words, since the end of the coil spring 7 is prevented from being elastically deformed as much as possible, it is possible to more reliably suppress the coil spring 7 from being fatigued or broken due to stress concentration.
For the same reason, not only the outer peripheral side wall surface of the second housing groove 3b but also the inner peripheral side wall surface may be thin, or both wall surfaces thereof may be thin.

  As described above, the pulley structure 1 of the present embodiment employs the coil spring 7 as an elastic body that elastically connects the first rotating body 2 and the second rotating body 3. That is, a cylindrical spring housing chamber 6 is provided between the first rotating body 2 and the second rotating body 3, a coil spring 7 is installed in the spring housing chamber 6, and one end thereof is formed in the first housing groove 2b. The other end is fixed to the second receiving groove 3b. Here, the coil spring 7 can have an allowable relative angular displacement larger than that of an annular rubber or the like because of the structural reason that the spring wire is wound spirally. Therefore, the allowable relative angular displacement between the first rotating body 2 and the second rotating body 3 can be increased, and rotational fluctuations can be absorbed efficiently. Along with this, fluctuations in the belt tension can be suppressed, so that belt resonance can be suppressed, whereby the generation of new noise in the belt can be prevented and the durability of the belt can be improved.

  Moreover, it is preferable that the 1st rotary body 2 is actively weight-reduced like the hollow part 2d shown, for example in FIG. Thereby, since the rotational moment of inertia of the first rotating body 2 can be reduced, the belt tension required to maintain the speed at a certain point of the pulley body 2a at the speed of the belt can be relaxed. Therefore, since generation | occurrence | production of the force exceeding the static friction force between the pulley body 2a and a belt can be suppressed, a belt is not worn out and a lifetime can be extended.

  Furthermore, it is preferable to employ a light alloy such as aluminum as a material of the first rotating body 2. Thereby, since the rotation inertia moment of the 1st rotary body 2 can further be reduced, there exists an effect that the lifetime of a belt can be extended similarly to the effect by the weight reduction by the above-mentioned thickness reduction.

In addition, since a damper member such as a viscous fluid is not used, the structure is simple and the number of parts can be reduced. Moreover, you may provide a damper member not only in this.
More specifically, the inside of the spring accommodating chamber 6 may be filled with a viscous fluid such as silicon oil. Thereby, a damping effect can be added to the relative rotational motion between the first rotating body 2 and the second rotating body 3. Further, even when a viscous fluid is used as the damper member in this way, it is not particularly necessary to devise the shape of the spring accommodating chamber 6 or the like, so that the manufacturing cost of the pulley structure 1 does not increase so much.

In this embodiment, a rectangular coil spring having a rectangular cross section is employed. Thereby, the following effects are obtained by comparing the coil spring having a circular cross section with the square coil spring. That is, with the same relative angular displacement, the same number of turns, and the same spring constant, the maximum tensile (compression) stress generated in the latter coil spring can be reduced to about 70%, while the same relative angular displacement. If the maximum tensile (compression) stress generated in the above is the same and the spring constant is the same, the latter required number of turns is 70%.
Although it is preferable to employ a square coil spring for the above reasons, the present invention is not limited to this, and the cross-sectional shape of the coil spring may be circular, for example.

  Moreover, in this embodiment, the edge part of the coil spring 7 is each accommodated in the 1st accommodating groove 2b and the 2nd accommodating groove 3b. Thus, by providing the end portions of the coil springs 7 in the first receiving grooves 2b and the second receiving grooves 3b, the coil springs 7 can be installed in a straight and stable manner without tilting. That is, if the coil spring 7 is installed at an inclination, an excessive force is likely to be applied to a part of the coil spring 7 due to rotational fluctuation applied to the pulley structure 1, and the coil spring 7 is likely to be damaged. In this respect, in the present embodiment, since the first housing groove 2b and the second housing groove 3b can reliably avoid the mounting direction of the coil spring 7 from being inclined, the rotational fluctuation applied to the pulley structure 1 is affected by the entire spring wire. It can be received evenly and the life of the coil spring 7 can be extended.

  Moreover, although this embodiment demonstrated the case where the pulley structure 1 was provided in the generator shaft of the alternator, it is not restricted to this, For example, installing the pulley of this invention in the compressor shaft of the air conditioner of a motor vehicle is considered. Further, the pulley may be provided on the power output side, for example, the crankshaft of the engine. In this case, the rotation of the crankshaft is transmitted from the second rotating body 3 to the first rotating body 2 via the coil spring 7, and power is output from the first rotating body 2 via the belt. Further, the application of the pulley structure of the present invention other than the vehicle equipment is not hindered, and the pulley structure of the present invention can be installed and used in various rotation transmission systems.

  Next, a modification of the pulley structure 1 according to the first embodiment of the present invention will be described with reference to FIG.

  FIG. 3 is a partial schematic view showing a modification of the pulley structure according to the first embodiment of the present invention, which is similar to FIG.

Moreover, the said modification can be changed as follows.
That is, as shown in FIG. 3, a meandering portion 7c having a wavy shape may be formed at the end 7b of the coil spring 7. In FIG. 3, instead of illustrating the outline before the coil spring 7 is press-fitted, the outline of the press-fit portion 11 before the press-fitting is represented by a two-dot chain line.
In other words, in FIG. 2, the both wall surfaces of the first receiving groove 2b are formed in a meandering shape, whereas in FIG. 3, the terminal end 7b of the coil spring 7 is formed in a meandering shape.
More specifically, before the coil spring 7 is press-fitted into the press-fit portion 11, the side surface of the meandering portion 7 c having a rectangular cross section that is gripped by the press-fit portion 11 is previously corrugated. It is formed in a shape.
Even in this case, similarly to the locking portion 2c ′ shown in FIG. 2, the coil spring 7 and the press-fitting portion 11 are alternately elastic to the inner peripheral side and the outer peripheral side along the circumferential direction of the first receiving groove 2b. The restoring force generated by the deformation is also alternately applied to the inner peripheral side and the outer peripheral side. Therefore, the frictional force between the coil spring 7 and the press-fit portion 11 can be greatly improved.

  Furthermore, in this modification, the first rotating body 2 provided with the first receiving groove 2b does not require any additional work for providing a meandering surface, and the coil spring 7 that is easy to process is simply Since the locking portion is configured only by providing the meandering portion 2e, it is possible to provide a pulley structure that is excellent in productivity and inexpensive.

  Next, based on FIG.4 and FIG.5, 2nd Embodiment of the pulley structure based on this invention is described.

  FIG. 4 is a cross-sectional view of a pulley structure according to the second embodiment of the present invention. 5 is a cross-sectional view taken along the line BB in FIG. Note that, in the second embodiment, members similar to the constituent members of the first embodiment are given the same reference numerals in principle.

  As shown in FIG. 4, when the first rotator 2 and the second rotator 3 are relatively rotated to a predetermined angle between the first rotator 2 and the second rotator 3, the angle is Rotation restricting portions 10 for restricting the relative rotation exceeding are provided in the vicinity of both end portions of the coil spring 7.

More specifically, as shown in FIG. 5, the rotation restricting portion 10 includes an arc-shaped first protrusion 2 f that protrudes from the inner peripheral wall of the first rotating body 2 toward the axis, and the first protrusion. The second projecting portion 3f is configured to be in contact with the portion 2f and projecting in an arc shape from the outer peripheral wall of the second rotating body 3.
The first protrusion 2f and the second protrusion 3f are provided in pairs with respect to the central axis of the pulley structure 1. The first protrusions 2f and the second protrusions 3f that are provided in pairs are alternately arranged in the circumferential direction.
With the above configuration, when the relative rotation angle between the first rotating body 2 and the second rotating body 3 is equal to or greater than a predetermined angle, further relative rotation is restricted. An upper limit is set for the deformation. In other words, since an upper limit is set for the stress generated in the coil spring 7, an excessive force does not act on the coil spring 7, thereby suppressing fatigue and breakage.

  Next, a modification of the second embodiment will be described with reference to FIG. FIG. 6 is a view similar to FIG. In this modification, members similar to those of the second embodiment are given the same reference numerals in principle.

As shown in FIG. 6, in this modification, a cylindrical spring holder 60 is provided on the outer peripheral side of the coil spring 7, and the spring holder 60 is fixed to the inner peripheral surface of the first rotating body 2. ing. Thereby, since the deformation amount in the diameter expansion direction of the coil spring 7 does not become excessive, damage due to excessive deformation of the coil spring 7 can be prevented.
The material of the spring holder 60 is preferably a synthetic resin material such as polyacetal, polyarylate, or nylon, a rubber material, a polyurethane elastomer material, or the like, but is not limited thereto.

Note that the spring holder 60 may be disposed on the outer peripheral side of the coil spring 7 as shown in FIG. 6 or may be disposed on the inner peripheral side although not shown. In the latter case, the amount of deformation of the coil spring 7 in the diameter reduction direction does not become excessive.
Of course, the spring holder 60 may be provided on the outer peripheral side and the inner peripheral side of the coil spring 7 simultaneously. According to this, the amount of deformation of the coil spring 7 in both the diameter expansion and contraction directions does not become excessive.
Further, by providing the spring holder 60, even if the coil spring 7 is deformed in an enlarged diameter (or reduced diameter), it directly rubs against the first rotating body 2 (or the second rotating body 3). Therefore, damage to the coil spring 7 can be suppressed. This is particularly useful when it is desired to make the space between the outer peripheral side (or inner peripheral side) of the coil spring 7 and the first rotating body 2 (or the second rotating body 3) as narrow as possible as shown in FIG. It is.
Although the spring holder 60 has been described as being cylindrical, there is no problem even if an appropriate slit or straight groove is provided on the peripheral wall.

Further, as shown in FIG. 6, a retainer groove 62 and a pressure groove 63 extending in parallel with the axial direction of the pulley structure 1 are formed on the circumferential surfaces of the first rotating body 2 and the second rotating body 3 facing each other. Each is recessed.
In addition, a disc-shaped retainer plate 64 and a pressure plate 65 are interposed between the opposing peripheral surfaces, and the former retainer plate 64 is partially fitted into the retainer groove 62 so that the pulley structure is provided. The body 1 is slidable in the axial direction, and rotation is restricted in the circumferential direction. Similarly, the latter pressure plate 65 is also slidable in the axial direction of the pulley structure 1 by being partially fitted in the pressure groove 63, and the rotation is restricted in the circumferential direction.

A disc-shaped friction member 66 is interposed between the retainer plate 64 and the pressure plate 65 so as to be sandwiched in the axial direction.
Further, a ring member 67 for fitting the axial center of the friction member 66 and the axial center of the pulley structure 1 is fitted on the outer peripheral surface of the friction member 66, and the ring member 67 is The inner periphery of the first rotating body 2 is inscribed so as to be slidable in both the circumferential direction and the axial direction.

Further, as shown in FIG. 6, the retainer plate 64 is engaged with the first rotating body 2 so as to be axially movable and relatively non-rotatable, and the pressure plate 65 causes the friction member 66 to move to the retainer plate 64. It is urged by appropriate urging means 68 in the direction to be pressed. Accordingly, the retainer plate 64 and the friction member 66, and the friction member 66 and the pressure plate 65 are in close contact with each other.
Since the retainer plate 64 is configured to rotate with the first rotating body 2 and the pressure plate 65 is configured to rotate with the second rotating body 3 as described above, the second rotating body 3 of the first rotating body 2 is configured. The relative rotational movement of the retainer plate 64 and the pressure plate 65 are damped by sliding with each other via the friction member 66.
In short, a friction member 66 is interposed between the first rotating body 2 and the second rotating body 3, and the first rotating body 2 and the second rotating body 3 are interposed via the friction member 66. Thus, the relative rotational motion is attenuated by sliding with each other.

  As shown in FIG. 6, in this modification, the urging means 68 is a disc spring. One end of the disc spring 68 abuts on the pressure plate 65, and the other end of the disc spring 68 is a retaining ring fitted in an annular locking groove 68a that is recessed in the circumferential direction on the outer peripheral surface of the second rotating body 3. 68b.

As described above, in this modification, the friction member 66 is interposed between the first rotating body 2 and the second rotating body 3. As a result, the relative rotational motion of the first rotating body 2 with respect to the second rotating body 3 is attenuated, and deformation of the coil spring 7 is also suppressed. As a result, a long-life pulley structure 1 can be obtained.
The material of the friction member 66 is preferably a synthetic resin material such as polyacetal, polyarylate, or nylon, a rubber material, a polyurethane elastomer material, or the like, and is not limited thereto.

Further, as described above, in the present modification, the friction member 66 is one of the first rotating body 2 and the second rotating body 3 (in the present modification, the first rotating body 2 and the retainer plate 64), The pressure plate 65 is interposed between the other (second rotating body 3 in this modification) and a pressure plate 65 that is slidable in the axial direction. The first rotator 2 and the retainer plate 64) are urged by appropriate urging means (a disc spring 68) in a direction to be pressed. Thereby, a large damping force is applied to the relative rotational movement of the first rotating body 2 with respect to the second rotating body 3.
Although the retainer plate 64 is provided, an appropriate frictional force (damping force) is generated between the first rotating body 2 and the friction member 66. However, the present invention is not limited to this, and is omitted. There is no problem.
The above configuration can be modified as follows, for example. That is, instead of the retainer plate 64, a flange is formed so as to protrude from the inner peripheral surface of the first rotating body 2, and the friction member 66 is pressed against the flat surface formed on the flange via the pressure plate 65. You may comprise so that a biasing means may be arrange | positioned.

  Next, a third embodiment of the pulley structure according to the present invention will be described. FIG. 7 is a view similar to FIG. For convenience of explanation, the first accommodation groove 2b (second accommodation groove 3b, hereinafter the same) formed in a curved shape (arc shape) is drawn in a straight line in this drawing. Moreover, in this embodiment, the same code | symbol is attached | subjected in principle to the member similar to the structural member of said 1st Embodiment.

As shown in FIG. 7, in the present embodiment, the first accommodation groove 2 b is formed wider than the coil spring 7. Further, as in the first embodiment and the second embodiment described above, the groove width of the first receiving groove 2b is constant without increasing or decreasing, and the side walls of the groove are always formed as so-called parallel grooves. . An end portion (press-fit portion 7a) of the coil spring 7 is formed with a wavy meandering portion 50 that is fitted into the press-fit portion 11 of the first receiving groove 2b by press-fitting.
Thus, as in the first embodiment described above, by using a coil spring for the elastic member as a means for gently absorbing the crankshaft rotational fluctuation, a larger relative angular displacement than when rubber or the like is used for the elastic member. Can be allowed and secured, and it is easier to absorb rotational fluctuations. Along with this, belt tension fluctuations can be suppressed, so that belt resonance can be suppressed, whereby the generation of new noise in the belt can be prevented and the durability of the belt can also be improved.
Further, since the bending deformation load of the coil spring 7 can be received by the entire meandering portion 50, stress concentration on the coil spring 7 at the time of rotational fluctuation can be prevented, and accordingly, the coil spring 7 at the end of the press-fit portion 11 can be prevented. Fatigue failure can be prevented.
Further, since the gap between the meandering portion 50 and the first receiving groove 2b is gradually increased or decreased, stress concentration on the coil spring 7 at the time of rotational fluctuation is prevented in this sense.
Moreover, since the said 1st accommodation groove | channel 2b is enough for a parallel groove | channel and does not require a special process, the cheap pulley structure 1 can be provided.

Further, as shown in the figure, it is preferable that the meandering portion 50 is in contact with the side wall of the first receiving groove 2b at at least three locations.
Thereby, since the locking force with respect to the edge part of the said coil spring 7 of the said 1st accommodation groove 2b can be enlarged, the said edge part slides with respect to the said 1st accommodation groove 2b, or the said 1st accommodation groove It can be prevented from being removed from 2b.
Further, since the end portion of the coil spring 7 is supported at three points with respect to the first housing groove 2b, the posture of the coil spring 7 can be stabilized.
Of course, the meandering portion 50 may be in contact with the side wall of the first receiving groove 2b at four or more locations.

Moreover, it is preferable that the press fitting allowance with respect to the said 1st accommodation groove | channel 2b of the said meandering part 50 is 0.1 mm or more and 0.5 mm or less. In the present embodiment, the press-fitting allowances are all in the range of 0.1 mm to 0.5 mm.
As described above, when the press-fitting allowance is 0.1 mm or more, the locking force of the first receiving groove 2b with respect to the end of the coil spring 7 is slid against the first receiving groove 2b. It can be ensured enough that it does not move or be removed from the first receiving groove 2b.
On the other hand, when the press-fitting allowance is 0.5 mm or less, the assemblability of the pulley structure 1 can be improved.

  Next, a modification of the third embodiment will be described with reference to FIG. FIG. 8 is a view similar to FIG.

In the present modification shown in FIG. 8, the meandering portion 50 is in contact with the side wall of the first housing groove 2b at five locations. The press-fitting allowance of the meandering portion 50 with respect to the first accommodation groove 2 b becomes smaller as the distance from the terminal end 7 b of the coil spring 7 increases.
According to this, the following problems can be solved.
That is, the stress generated at the end portion (press-fit portion 7a) of the coil spring 7 increases as the distance from the end 7b increases. In other words, stress unevenness occurs in which the generated stress is maximized at the end portion (press-fit portion 7a) farthest from the terminal end 7b.
Therefore, according to the present modification, the above problem can be solved, so that the life of the coil spring 7 can be extended.
From another point of view, by reducing the press-fitting allowance of the portion X where the bending deformation load of the coil spring 7 acts most, the repeated stress acting on the portion X is suppressed, so that the life of the coil spring 7 is reduced. Can be extended.

  More specifically, the press-fitting allowance of the meandering portion 50 with respect to the first receiving groove 2b is less than 0.1 mm (press-fitting allowance: small) on the side far from the end 7b of the coil spring 7, and 0 on the close side. It is preferable that it is 1 mm or more (press-fit allowance: large). Thereby, said effect is show | played more reliably.

  Moreover, also in the said 3rd Embodiment and the said modification, it is preferable that the said coil spring 7 is a square coil spring with a rectangular cross section. The effect of this is as described above.

  Next, a fourth embodiment of the pulley structure according to the present invention will be described. FIG. 9 is a view similar to FIG. In FIG. 9 as well, for convenience of explanation, the first accommodation groove 2b (second accommodation groove 3b, hereinafter the same) formed in a curved shape (arc shape) is drawn in a straight line. Also in this embodiment, members similar to those of the first embodiment are given the same reference numerals in principle.

As shown in FIGS. 9A to 9C, the first receiving groove 2 b is formed wider than the coil spring 7 in this case as well. In addition, two wide portions 51 are formed on the end portion (press-fit portion 7a) of the coil spring 7 to be fitted into the press-fit portion 11 of the first receiving groove 2b by press-fitting. Moreover, the contact part 51a vicinity with respect to the said 1st accommodation groove | channel 2b of the said wide part 51 is formed in curve shape.
Thus, as in the first embodiment described above, by using a coil spring for the elastic member as a means for gently absorbing the crankshaft rotational fluctuation, a larger relative angular displacement than when rubber or the like is used for the elastic member. Can be allowed and secured, and it is easier to absorb rotational fluctuations. Along with this, belt tension fluctuations can be suppressed, so that belt resonance can be suppressed, whereby the generation of new noise in the belt can be prevented and the durability of the belt can also be improved.
Further, since the gap between the wide portion 51 and the first receiving groove 2b is configured to gradually increase or decrease, stress concentration on the coil spring 7 at the time of rotational fluctuation can be prevented, and accordingly, at the end of the press-fit portion 11 The fatigue failure of the coil spring 7 can be prevented.
Further, since the first receiving groove 2b is sufficient as a parallel groove having a constant width and does not require special processing, an inexpensive pulley structure 1 can be provided.

Moreover, since the said wide part 51 is formed in two places, there exist the following effects.
That is, since the locking force of the first receiving groove 2b to the end of the coil spring 7 can be increased, the end slides with respect to the first receiving groove 2b or the first receiving groove 2b. It can be prevented from being pulled out from.
Moreover, since the edge part of the coil spring 7 is supported by 3 or more points (4 points) with respect to the 1st accommodation groove | channel 2b, the attitude | position of the coil spring 7 can be stabilized.
Further, since the bending deformation load of the coil spring 7 is shared and supported by the four contact portions 51a as shown in FIG. 9A, the stress concentration on the coil spring 7 at the time of rotation fluctuation is increased. More reliably prevented.
Of course, the wide portions 51 may be formed at three or more locations.

The wide portion 51 is formed by pressing the peripheral wall of the coil spring 7. In other words, the wide portion 51 is formed by pressing the coil spring 7 in a direction perpendicular to the longitudinal direction. Thereby, the said wide part 51 can be formed at low cost. Moreover, since the magnitude | size (width | variety) of the said wide part 51 can be changed freely only by adjusting the amount of presses, the cost increase accompanying a design change can be suppressed, for example.
The press work may be in various forms as exemplified in FIGS. 9 (a) to 9 (c). In these drawings, a square coil spring is employed as the coil spring 7.
For example, as shown in FIG. 9A, only the center of the peripheral wall (side wall) of the coil spring 7 is appropriately pressed so that the coil spring 7 expands and deforms in the groove width direction of the first receiving groove 2b. May be.
Further, as shown in FIG. 9B, press working may be used in which the peripheral wall (side wall) of the coil spring 7 is crushed by a flat member.
Further, as shown in FIG. 9 (c), the press work is such that the hole is expanded in the radial direction by pressing a punch tool or the like into the hole previously opened in the peripheral wall (side wall) of the coil spring 7. May be. In addition, it is conceivable that the press work is performed only from one side of the hole and from both sides. In the former case, a frustoconical hole is formed, and in the latter case, as shown in this figure. A long drum-shaped hole will be formed.

Also in this embodiment, as in the third embodiment, it is preferable that the allowance for press-fitting the wide portion 51 into the first accommodation groove 2b is 0.1 mm or more and 0.5 mm or less. Similarly, it is preferable that the press-fitting allowance decreases as the distance from the terminal end 7 b of the coil spring 7 increases.
Further, the press-fitting allowance is preferably less than 0.1 mm on the side far from the end 7 b of the coil spring 7 and 0.1 mm or more on the near side.
The effect by these is as having described when explaining 3rd Embodiment.

  In the present embodiment, the coil spring 7 is a square coil spring as in the first to third embodiments, but the function and effect of this are also as described above.

The third and fourth embodiments and their modifications may be modified as follows.
In other words, the end 7b of the coil spring 7 may be formed with a winding portion that further extends in an arc shape along the first receiving groove 2b and has a surface perpendicular to the coil axis. . The wrapping portion has a shape that gradually becomes thinner toward the end, for example, a thin portion of the spring formed when the coil spring 7 is simply cut along a plane perpendicular to the coil axis. means.
As a result, the auxiliary winding portion of the coil spring 7 and the bottom surface of the first receiving groove 2b to which the auxiliary winding portion is press-fitted and fixed can be brought into surface contact. This can be prevented and the assembly workability is improved. In addition, the said center blurring means the blurring with respect to the rotating shaft center of the said pulley structure 1 of the coil axial center of the coil spring 7, for example.
In addition, the meandering part 50 and the wide part 51 may be formed in the auxiliary winding part.
Moreover, it is preferable that the auxiliary winding part is provided about 3/4 round. As a result, it is possible to more effectively prevent the center shake of the coil axis of the coil spring 7.

  The groove width of the first receiving groove 2b is preferably constant as described above. Thereby, since the process of the said 1st accommodation groove | channel 2b can be made easy, an inexpensive pulley structure can be provided.

  Next, a fifth embodiment of the pulley structure according to the present invention will be described. 10 is a cross-sectional view of a pulley structure according to a fifth embodiment of the present invention, and FIG. 11 is a cross-sectional view taken along the line EE in FIG.

  In the fifth embodiment, as shown in FIG. 10, the first rotating body 2 and the second rotating body 3 are each provided with a first flange portion 41 'and a second flange portion 42'. The first flange portion 41 ′ is integrally formed with the first rotating body 2, and the second flange portion 42 ′ is integrally formed with the second rotating body 3. The spring accommodating chamber 6 for accommodating the coil spring 7 is formed in a space sandwiched in the axial direction by two flange portions 41 ′ and 42 ′.

  A dry metal type bearing 4 is interposed between the first flange portion 41 ′ and the second rotating body 3. The second rotating body 3 is configured as a cylindrical hub and is fitted on the drive shaft DS of the alternator. The tip of the drive shaft DS of the alternator is screwed into the shaft hole 3a of the second rotating body 3.

  The first flange portion 41 ′ is formed with a first receiving groove 2 b for press-fitting and embedding one end of the spring wire of the coil spring 7. This 1st accommodation groove | channel 2b is comprised as a circular arc groove | channel extended in the circumferential direction so that a spring line may be followed, as shown in FIG. 11 as an EE cross-sectional arrow view of FIG.

  In a part of this arc groove (partial region on the end side of the spring wire), fine irregularities 2h by serration processing or knurl processing are formed on the inner wall, and the press-fit locking portion 46 (region where the irregularities are provided) is formed. Is formed. On the other hand, in a region other than the press-fitting locking portion 46, a press-fitting portion 47 (a region where no unevenness is provided) is formed.

The coil spring 7 has irregularities formed at positions corresponding to the irregularities 2 h of the press-fit locking portion 46. The irregularities are formed by serration processing or knurling.
With this configuration, one end of the spring wire is mechanically engaged with the concave and convex portion 2 h of the press-fit locking portion 46 and is press-fitted and fixed at the press-fit portion 47. In this way, by combining the engagement and fixing at the press-fitting locking portion 46 and the press-fitting and fixing at another region (press-fit portion 47), the end of the coil spring 7 can be stabilized and the first flange portion 41 ′ can be fixed. 1 can be fixed to the receiving groove 2b.

  Since the fixing of the other end side of the coil spring 7 to the second receiving groove 3b of the second flange portion 42 'is the same as the fixing to the first flange portion 41', description thereof is omitted. Note that such a configuration in which the engagement and fixing at the press-fitting locking portion and the press-fitting and fixing at other regions are used together can be applied only to one end side of the coil spring 7.

  As described above, in this embodiment, the concave and convex portions 2h are provided on at least a part of the inner walls of the housing grooves 2b and 3b, and the end portion of the coil spring 7 that does not meander is formed on the inner wall (press-fit locking) having the concave and convex portions 2h. The portion 46 is press-fitted and fixed. By adopting this configuration, processing that causes the end of the coil spring 7 to meander becomes unnecessary, and an inexpensive pulley structure can be provided. Further, the end of the coil spring 7 can be firmly fixed to the receiving grooves 2b and 3b through the unevenness 2h. Furthermore, since the end portion of the coil spring 7 is press-fitted and fixed to the inner walls of the housing grooves 2b and 3b, the end portion of the coil spring 7 can be firmly press-fitted and fixed via the unevenness 2h so as not to come off.

  In addition, at the end of the coil spring 7, a region (an area corresponding to the press-fit engagement part 46) that is locked and fixed via the unevenness 2 h and a region (an equivalent to the press-fit part 47) that is locked and fixed by press-fitting. A region to be formed). As a result, both the mechanically locked region and the press-fitted fixing region are secured, so that both the mechanical locking action and the press-fit fixing action of the unevenness can be fully exhibited.

  The preferred embodiments of the present invention have been described above. However, the above-described embodiments can be modified as follows.

  In addition, the configuration is not limited to the configuration in which both ends of the coil spring 7 are fixed in the configuration described in the above embodiment. For example, only one end side is fixed in any of the above embodiments, and the other end side is in another configuration. It may be fixed. Moreover, in the part of the brazing fixing part used in the above embodiment, fixing with an adhesive may be employed instead.

DESCRIPTION OF SYMBOLS 1 Pulley structure 2 1st rotary body 2b 1st accommodating groove 2f 1st projection part 2h Concavity and convexity 3 2nd rotary body 3b 2nd accommodation groove 3f 2nd projection part 4, 5 Bearing 6 Spring accommodating chamber 7 Coil spring 7a Press fit Parts 7c, 50 meandering part 11 press-fitting part 46 press-fitting locking part (area provided with irregularities)
47 Press-fit part (area where unevenness is not provided)
51 Wide portion 60 Spring holder 65 Pressure plate 66 Friction member 68 Biasing means

Claims (15)

A first rotating body that allows the belt to be wound;
A second rotating body that is rotatable relative to the first rotating body inside the first rotating body;
A spring accommodating chamber formed between the first rotating body and the second rotating body;
In the pulley structure comprising a coil spring housed in the spring housing chamber, one end fixed to the first rotating body and the other end fixed to the second rotating body,
At least one of the first rotator and the second rotator includes an arcuate accommodation groove that accommodates an end of the coil spring,
The receiving groove has a press-fit portion where the press-fit portion of the coil spring is press-fitted and fixed,
Concavities and convexities are formed on the side wall of the press-fitting portion in the circumferential direction of the housing groove,
Concavities and convexities that engage with the concavities and convexities of the press-fitting part are formed in a portion facing the side wall of the press-fitting part,
2. The pulley structure according to claim 1, wherein the press-fitted portion is supported in contact with the side wall of the press-fitted portion at at least three locations. 2. The pulley structure according to claim 1 , wherein the press-fitted portion or the press-fitted portion has a region where the unevenness is provided and a region where the unevenness is not provided. The pulley structure according to claim 1 or 2 , wherein the unevenness is formed by serration processing or knurling processing.   A first rotating body that allows the belt to be wound;
  A second rotating body that is rotatable relative to the first rotating body inside the first rotating body;
  A spring accommodating chamber formed between the first rotating body and the second rotating body;
  In the pulley structure comprising a coil spring housed in the spring housing chamber, one end fixed to the first rotating body and the other end fixed to the second rotating body,
  At least one of the first rotator and the second rotator includes an arcuate accommodation groove that accommodates an end of the coil spring,
  The receiving groove has a press-fit portion where the press-fit portion of the coil spring is press-fitted and fixed,
  The pulley structure according to claim 1, wherein at least two wide portions that contact the side wall of the press-fit portion are formed in the press-fit portion. The pulley structure according to claim 4 , wherein the wide portion is formed by pressing a peripheral wall of the coil spring. The pulley structure according to any one of claims 1 to 5 , wherein a press-fitting allowance of the press-fitted part to the press-fitted part is 0.1 mm or more and 0.5 mm or less. The pulley structure according to any one of claims 1 to 6 , wherein a press-fitting margin of the press-fitted portion with respect to the press-fitted portion decreases as the distance from the terminal end of the coil spring decreases. The pulley structure according to claim 7 , wherein the press-fitting allowance is less than 0.1 mm on the side far from the end of the coil spring and 0.1 mm or more on the near side. Pulley structure according to any one of claims 1-8 in which the groove width of the press-in portion is constant, it is characterized. The end of the coil spring, according to claim 1-8, wherein the extending accommodating further along the groove, and添巻portion having a surface perpendicular to the coil axis is formed, it is characterized by The pulley structure according to any one of the above. Pulley structure according to any one of claims 1-10 wherein the coil spring is the cross-section is a rectangular square coil spring, characterized in that. At least one first protrusion is provided on the inner peripheral wall of the first rotating body;
At least one second protrusion that can contact the first protrusion is provided on the outer peripheral wall of the second rotating body,
The pulley structure according to any one of claims 1 to 11 , wherein when the first rotating body and the second rotating body relatively rotate to a predetermined angle, the relative rotation exceeding the angle is restricted. Pulley structure according to any one of claims 1 to 12, a friction member between the first rotor and the second rotor is interposed, it is characterized. The friction member is interposed between any one of the first rotating body and the second rotating body and a pressure plate slidably provided on the other,
The pulley structure according to claim 13 , wherein the pressure plate is urged by appropriate urging means in a direction to press the friction member against the one side. The pulley structure according to any one of claims 1 to 14 , wherein a cylindrical spring holder is provided on at least one of an outer peripheral side and an inner peripheral side of the coil spring.

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