Patent Description:
To an accessory machine having a large moment of inertia, such as an alternator driven by power of an engine of an automobile and the like, is connected, for example, a pulley structure described in PTL <NUM> for the purpose of absorbing fluctuations in the rotational speed of the crankshaft of the engine.

The pulley structure described in PTL <NUM> includes: an outer rotating body around which a belt is to be wound; an inner rotating body provided radially inward on the outer rotating body and relatively rotatable with respect to the outer rotating body; a torsion coil spring disposed in spring accommodation space formed between the two rotating bodies; and the like. The pulley structure has a clutch mechanism that transmits or blocks torque between the outer rotating body and the inner rotating body via the torsion coil spring.

Since the two rotating bodies are made of metal, when rust is generated and interposed between the torsion coil spring and the rotating bodies, the function of the clutch mechanism and the like may be reduced and the life may be shortened. Therefore, a coating for rust prevention is applied to several portions. On the other hand, for example, in a portion in contact with the torsion coil spring in the spring accommodation space and the like, the coating may be peeled off, so that a grease containing a rust inhibitor is used instead of the coating. More specifically, when assembling the pulley structure, the grease is put into the spring accommodation space in a pasty lump state. Since the grease has high viscosity at normal temperature and is less likely to flow, the temperature in the spring accommodation space is raised by running the pulley structure in, for example, an operation test of the alternator, and the temperature of the grease is raised to lower the viscosity. When the pulley structure is made to rotate in this state, the rust inhibitor is diffused to a portion of the two rotating bodies facing the spring accommodation space by centrifugal force and the like. In this way, compared to the case where the rust inhibitor is adhered to the entire region facing the spring accommodation space one by one, the labor is significantly reduced, and the use amount of rust inhibitor can be minimized.

Further related art may be found in <CIT> which describes an overrunning alternator decoupler pulley with bare wire spring and grease lubrication, in <CIT> which describes an overrunning decoupler and in <CIT> which describes a pulley structure.

When the grease is simply put into the spring accommodation space in a lump state, the grease may be in a state of coming into contact with only an unspecified portion of the spring accommodation space. In this case, heat is less likely to be transferred to the grease due to reasons such as a small heat-transfer area and thus, the viscosity is less likely to decrease. Therefore, when the pulley structure is rotated, it may be difficult to diffuse the grease to every corner of the region facing the spring accommodation space of the two rotating bodies.

An object of the present invention is to facilitate diffusion of the rust inhibitor over the entire region facing the spring accommodation space.

The dependent claims describe optional features and distinct embodiments.

The pulley structure in a first aspect of the present invention is a pulley structure to be connected to an accessory machine of an engine and to which power of the engine is to be transmitted via a belt, the pulley structure including: a cylindrical outer rotating body around which the belt is to be wound; an inner rotating body provided radially inward on the outer rotating body and relatively rotatable with respect to the outer rotating body; and a torsion coil spring disposed in a spring accommodation space formed between the outer rotating body and the inner rotating body, in which at least in a state where the pulley structure is not yet operated once, a grease containing a rust inhibitor is applied to a facing surface of the inner rotating body, facing an inner circumferential surface of the torsion coil spring.

According to the pulley structure of the present invention, in a state where the pulley structure is not yet operated once, the grease containing a rust inhibitor is in a state of being applied to the facing surface of the inner rotating body, facing the inner circumferential surface of the torsion coil spring. As a result, since the contact area with the inner rotating body is larger as compared to the case where the grease is simply put in the spring accommodation space in a lump state, heat of the inner rotating body is likely to be transferred to the grease during the operation test of the accessory machine and the like, the temperature of the grease is likely to be raised, and the viscosity is likely to decrease. In addition, since the grease is applied to the facing surface disposed radially inward among surfaces forming the spring accommodation space, the grease is likely to spread over the inner rotating body, and the centrifugal force due to the rotation of the inner rotating body acts on the grease, and thus the grease is also likely to be diffused radially outward. Therefore, the rust inhibitor can be made to be easily diffused in the entire region facing the spring accommodation space.

In the pulley structure according to a second aspect of the present invention, in the first aspect, the grease has a thickness of <NUM> or less on the facing surface.

In order to facilitate the transfer of the heat of the inner rotating body to the entire grease, the thickness of the grease on the facing surface is preferably <NUM> or less.

In the pulley structure according to a third aspect of the present invention, in the first or second aspect, the grease has an adhering area to the facing surface being <NUM>% or more of the area of the facing surface.

In this aspect, the adhering area of the grease to the facing surface is <NUM>% or more of the area of the facing surface. That is, since the heat-transfer area of the grease is large, heat of the inner rotating body is easily transferred to the grease.

In the pulley structure according to a fourth aspect of the present invention, in any one of the first to third aspects, the grease is applied on the facing surface along a rotation axis direction of the inner rotating body.

In the radial direction, since the centrifugal force due to the rotation of the inner rotating body acts on the grease during the operation test of the accessory machine and the like, the grease is likely to be diffused to outside. However, in the rotation axis direction, since no particularly large force acts on the grease, the grease is relatively less likely to be diffused. In this aspect, since the grease is applied on the facing surface along the rotation axis direction of the inner rotating body, the grease can be easily diffused in the rotation axis direction.

In the pulley structure according to a fifth and compulsory aspect of the present invention, in any one of the first to fourth aspects, the grease is applied only to the facing surface of the inner rotating body among surfaces forming the spring accommodation space.

In this aspect, the grease is applied only to the facing surface of the inner rotating body among the surfaces forming the spring accommodation space. Therefore, it is possible to efficiently diffuse the grease in the spring accommodation space by the rotation of the inner rotating body while reducing the labor as compared to the case where the grease is also applied to other places.

The pulley structure according to a sixth aspect of the present invention, in any one of the first to fifth aspects, includes a sliding bearing interposed between the inner rotating body and an end portion of the outer rotating body in a rotation axis direction.

When the outer rotating body corrodes and rust is generated in the gap between the outer rotating body and the sliding bearing, the bearing function may significantly deteriorate. Therefore it is necessary to diffuse the rust inhibitor on the surface of the outer rotating body, facing to the sliding bearing. However, in the case where the grease is applied only to the outer rotating body, even when the pulley structure is operated to rotate, a force radially inward does not act on the grease, and the grease is less likely to be diffused into the inner rotating body. On the other hand, in the case where the grease is applied to both the inner rotating body and the outer rotating body, labor is required and production efficiency is reduced. In this aspect, since the grease is applied to the facing surface of the inner rotating body, the grease is likely to be diffused into both the inner rotating body and the outer rotating body. Therefore, even in the case where the grease is not applied to the outer rotating body, the rust inhibitor is spread to the end portion of the outer rotating body in the rotation axis direction, and the generation of rust in the portion can be suppressed. Therefore, the bearing function can be maintained for a long period of time while suppressing a decrease in production efficiency.

In the pulley structure according to a seventh aspect of the present invention, in the sixth aspect, the sliding bearing is formed of a resin composition containing polytetramethylene adipamide as a base resin, and the resin composition contains a reinforcing material containing aramid fibers.

According to this aspect, since wear resistance and strength of the sliding bearing can be increased in a relatively high temperature range, the bearing function can be maintained for a longer period of time.

In the pulley structure according to an eighth aspect of the present invention, in the first to seventh aspects, the accessory machine is an alternator that generates electricity by the rotation of a drive shaft.

When the pulley structure is connected to the alternator and rotates, large heat is generated with power generation due to driving of the alternator, and is transmitted to the pulley structure. Therefore, the temperature of the grease can be sufficiently raised.

The method for manufacturing a pulley structure according to a ninth aspect of the present invention is a method for manufacturing a pulley structure to be connected to an accessory machine of an engine and to which power of the engine is to be transmitted via a belt, in which the pulley structure includes: a cylindrical outer rotating body around which the belt is to be wound; an inner rotating body provided radially inward on the outer rotating body and relatively rotatable with respect to the outer rotating body; and a torsion coil spring disposed in a spring accommodation space formed between the outer rotating body and the inner rotating body, and in which the method includes: applying a grease containing a rust inhibitor to a facing surface of the inner rotating body, facing an inner circumferential surface of the torsion coil spring.

In the manufacturing method of the present invention, since the grease is applied to the facing surface of the inner rotating body, the contact area between the grease and the inner rotating body becomes larger as compared to the case where the grease is simply put into the spring accommodation space in a lump state. Therefore, heat of the inner rotating body is likely to be transferred to the grease during the operation test of the accessory machine and the like. In addition, since the grease is applied to the facing surface of the inner rotating body disposed radially inward among the surfaces forming the spring accommodation space, the grease is likely to spread over the inner rotating body, and the centrifugal force due to the rotation of the inner rotating body acts on the grease, so that the grease is also likely to be diffused to the outer side in the radial direction.

The method for manufacturing a pulley structure according to a tenth aspect of the present invention, in the ninth aspect, includes: after applying of the grease, connecting the pulley structure to the accessory machine, and transmitting a power of a drive source to the pulley structure via the belt to operate the pulley structure.

In this aspect, after applying of the grease, the pulley structure is actually connected to the accessory machine, and the power of the drive source is transmitted to the pulley structure via the belt to operate the pulley structure. As a result, the grease can be diffused to the surfaces forming the spring accommodation space due to the temperature rise of the spring accommodation space with the rotation operation of the pulley structure, the centrifugal force acting on the grease by the rotation of the inner rotating body, and the like.

The method for manufacturing the pulley structure according to the eleventh aspect of the present invention, includes, in the ninth or tenth aspect, mounting the torsion coil spring on the inner rotating body, then, inserting a nozzle of discharging the grease into a gap in the radial direction between the torsion coil spring and the inner rotating body from one side in a rotation axis direction of the inner rotating body, and applying the grease to the facing surface.

When the grease is applied to the inner rotating body before the torsion coil spring is mounted on the inner rotating body, a part of the grease adheres to the torsion coil spring at the time when the torsion coil spring is mounted, and heat of the inner rotating body may be less likely to be transmitted. In this aspect, after the torsion coil spring is mounted on the inner rotating body, the nozzle is inserted into the gap between the torsion coil spring and the inner rotating body and the grease is applied to the facing surface. Accordingly, it is possible to prevent the grease from adhering to the torsion coil spring.

In the method for manufacturing a pulley structure according to a twelfth aspect of the present invention, in the eleventh aspect, the grease is discharged from a discharge port while moving the nozzle from the other side to the one side in the rotation axis direction.

In this aspect, since the grease is applied to the facing surface while the nozzle is simply drawn out from the other side to the one side, that is, toward the side where the nozzle is inserted, in the rotation axis direction, the grease can be easily applied.

In the method for manufacturing a pulley structure according to a thirteenth and compulsory aspect of the present invention, in any one of the ninth to twelfth aspects, the grease is applied only to the facing surface of the inner rotating body among surfaces forming the spring accommodation space.

In this aspect, since the grease is applied only to the facing surface of the inner rotating body among the surfaces forming the spring accommodation space, it is possible to efficiently diffuse the grease by the rotation of the inner rotating body while reducing the labor as compared to the case where the grease is also applied to other places.

Next, an embodiment of the present invention will be described with reference to <FIG>.

First, an example of a belt power-transmission mechanism in which a pulley structure <NUM> described later is incorporated will be described with reference to <FIG> is a front view of the belt power-transmission mechanism <NUM>, and <FIG> is a side view thereof. The belt power-transmission mechanism <NUM> includes, for example: a crank pulley <NUM> connected to a crankshaft <NUM> of an engine <NUM> of an automobile or the like; a pulley structure <NUM> connected to a drive shaft <NUM> of an alternator <NUM> ("accessory machine" of the present invention); an AC pulley <NUM> connected to an air conditioner compressor, which is not illustrated; a WP pulley <NUM> connected to a water pump, which is not illustrated; and a belt B (V-ribbed belt) wound around these pulleys. Each of the pulleys is rotatably supported. An auto-tensioner <NUM> is provided in the belt span between the crank pulley <NUM> and the pulley structure <NUM>. The output of the engine <NUM> is transmitted clockwise from the crank pulley <NUM> to the pulley structure <NUM>, the WP pulley <NUM>, and the AC pulley <NUM> via the belt B, and the respective accessory machines are driven.

Next, the configuration of the finished pulley structure <NUM>, that is, the pulley structure <NUM> at the time of shipment will be described. <FIG> is a cross-sectional view of the finished pulley structure <NUM>. <FIG> is a cross-sectional view taken along the line III-III in <FIG>. <FIG> is a cross-sectional view taken along the line IV-IV in <FIG>. For convenience of description, a left-right direction in the drawing of <FIG> is referred to as a front-rear direction ("rotation axis direction" of the present invention), the left side of the drawing, which is tip end side of the pulley structure <NUM>, is referred to as the front ("the other" of the present invention), and the right side of the drawing, which is the base end side of the pulley structure <NUM>, is referred to as the rear ("one" of the present invention). The direction in which the pulley structure <NUM> rotates is defined as a circumferential direction. The radial direction of the outer rotating body <NUM> to be described later is defined as a radial direction.

The pulley structure <NUM> is mainly connected to the alternator <NUM> that generates AC electricity by the rotation of the drive shaft <NUM>. As illustrated in <FIG>, the pulley structure <NUM> includes: an outer rotating body <NUM> around which the belt B is to be wound; an inner rotating body <NUM> provided inside the outer rotating body <NUM> and connected to the driving shaft <NUM> of the alternator; a torsion coil spring <NUM> (hereinafter, simply referred to as "spring <NUM>") disposed between the outer rotating body <NUM> and the inner rotating body <NUM>; and the like.

The outer rotating body <NUM> is a substantially cylindrical member in which a through hole penetrating in the front-rear direction is formed, and is, for example, a metal member made of carbon steel material such as S45C and the like. As illustrated in <FIG>, the belt B is wound around the outer circumferential surface of the outer rotating body <NUM>. The outer rotating body <NUM> is configured to rotate around a rotation axis R by applying torque via the belt B. On an inner circumference of a rear end portion of the outer rotating body <NUM>, a pressure contact surface <NUM> with which an outer circumferential surface <NUM> of a rear end portion of a spring <NUM> to be described later comes into contact is formed. An abutting surface <NUM> that abuts the spring <NUM> when it deforms to expand the diameter is formed in front of the pressure contact surface <NUM>. The abutting surface <NUM> is formed radially outward of the pressure contact surface <NUM>. A portion between the pressure contact surface <NUM> and the abutting surface <NUM> is chamfered. A bearing-interposing surface <NUM> in which a sliding bearing <NUM> to be described later is interposed is formed in front of the abutting surface <NUM>. The bearing-interposing surface <NUM> is formed radially outward of the abutting surface <NUM>. A portion between the abutting surface <NUM> and the bearing-interposing surface <NUM> is chamfered. An end cap <NUM> for covering an opening portion in the front of the outer rotating body <NUM> is attached to a front end portion of the outer rotating body <NUM>.

A rust-proof coating (e.g., cationic electrodeposition coating) is applied to the outer circumferential surface of the outer rotating body <NUM>, both end surfaces in the axial direction, and the chamfered portions. On the other hand, in order to maximize various functions of the pulley structure <NUM>, no coating is applied to portions other than the chamfered portions among the inner circumferential surface of the through hole of the outer rotating body <NUM> (the pressure contact surface <NUM>, the abutting surface <NUM>, the bearing-interposing surface <NUM>, etc.).

In the coating, it is necessary to consider to optimize the dimension (size of the chamfer) of a corner portion <NUM> and the like, where a coating material is difficult to attach, on the outer circumferential surface of the outer rotating body <NUM> depending on the coating material or the coating method, to thereby enhance the adhesion of the coating film to the corner portion <NUM>. When the adhesion of the coating film to the corner portion <NUM> is insufficient and rust is generated in the corner portion <NUM>, the coating film may be peeled off from the corner portion <NUM> as a starting portion. Alternatively, the rust grows on the interface between the coating film and the base (outer rotating body <NUM>), and the rust liberated from the corroded portion enters the inside of the spring accommodation space <NUM> to be described later (particularly, a place where the sliding bearing <NUM> is disposed). For this reason, it is desirable that the corner portion <NUM> be, for example, an R surface having a radius of curvature of approximately <NUM> or more, or a C surface.

The inner rotating body <NUM> is a metal member having a substantially cylindrical shape, and is, for example, a metal member made of carbon steel material such as S45C and the like. As illustrated in <FIG>, the inner rotating body <NUM> is provided radially inward on the outer rotating body <NUM> and is configured to be relatively rotatable with respect to the outer rotating body <NUM> around a common rotation axis R with the outer rotating body <NUM>. The above-described coating is not applied to the inner rotating body <NUM>.

The inner rotating body <NUM> includes: a cylindrical main body <NUM>; an outer cylindrical portion <NUM> disposed radically outward on the front end portion of the cylindrical main body <NUM>; a connection portion <NUM> connecting the cylindrical main body <NUM> and the outer cylindrical portion <NUM>; and the like. The cylindrical main body <NUM> is connected to the drive shaft <NUM> of the alternator. A press-fit surface <NUM> for press-fitting a rolling bearing <NUM> to be described later is formed at a rear end portion of the cylindrical main body <NUM>. A facing surface <NUM> facing an inner circumferential surface <NUM> of the spring <NUM> to be described later is formed in front of the press-fit surface <NUM>. The facing surface <NUM> is formed radially outward on the press-fit surface <NUM>. A contact surface <NUM> that comes into contact with the inner circumferential surface of the spring <NUM> is formed in front of the facing surface <NUM>. The contact surface <NUM> is formed radially outward on the facing surface <NUM>.

The outer cylindrical portion <NUM> is a cylindrical portion disposed radially outward on the front end portion of the cylindrical main body <NUM>. The outer cylindrical portion <NUM> extends rearward to the extent not to interfere with the outer rotating body <NUM>. An inner diameter of the outer cylindrical portion <NUM> is larger than a diameter of the pressure contact surface <NUM> of the outer rotating body <NUM>. The connection portion <NUM> is formed radially outward on the front end portion of the cylindrical main body <NUM> and is an annular portion connecting the cylindrical main body <NUM> and the outer cylindrical portion <NUM>.

An end surface <NUM> is formed between the cylindrical main body <NUM> and the outer cylindrical portion <NUM> at the front end portion of the inner rotating body <NUM> (see <FIG>). The end surface <NUM> faces a front end surface <NUM> of the spring <NUM> to be described later in the circumferential direction. A projection <NUM> projecting radially inward on the outer cylindrical portion <NUM> is formed on the inner circumferential surface of the outer cylindrical portion <NUM> (see <FIG>). The projection <NUM> is formed in the vicinity of a position approximately <NUM>° apart from the end surface <NUM> in the circumferential direction.

A rolling bearing <NUM> is interposed between the inner circumferential surface of the rear end portion of the outer rotating body <NUM> and an outer circumferential surface of the rear end portion of the cylindrical main body <NUM> of the inner rotating body <NUM>. A sliding bearing <NUM> is interposed between the inner circumferential surface of the front end portion of the outer rotating body <NUM> and the outer circumferential surface of the outer cylindrical portion <NUM> of the inner rotating body <NUM>. The outer rotating body <NUM> and the inner rotating body <NUM> are relatively rotatable by the rolling bearing <NUM> and the sliding bearing <NUM>.

The rolling bearing <NUM> is, for example, a contact seal type hermetic ball bearing. The sliding bearing <NUM> is, for example, a C-shaped member having elasticity and formed of a resin composition containing a resin of polytetramethylene adipamide (nylon <NUM>) as a base resin (main component). In addition, the resin composition may contain a fibrous reinforcing material having aramid fibers. As a result, wear resistance and strength of the sliding bearing <NUM> are increased at a relatively high temperature range (e.g., <NUM> to <NUM>), and the bearing function is maintained for a longer period of time. The sliding bearing <NUM> is mounted on the outer cylindrical portion <NUM> of the inner rotating body <NUM> in a state where the diameter thereof is made slightly expand, and is in close contact with the outer cylindrical portion <NUM> by a self-elastic-restoring force. A gap of approximately <NUM> in the radial direction is formed between the sliding bearing <NUM> and the bearing-interposing surface <NUM> of the outer rotating body <NUM>. The gap allows air to pass therethrough.

A spring accommodation space <NUM> for accommodating the spring <NUM> is formed between the outer rotating body <NUM> and the inner rotating body <NUM>. Specifically, the spring accommodation space <NUM> is a space defined by the inner circumferential surface of the outer rotating body <NUM>, the inner circumferential surface of the outer cylindrical portion <NUM> of the inner rotating body <NUM>, the outer circumferential surface of the cylindrical main body <NUM>, the rear surface of the connection portion <NUM>, and the front surface of the rolling bearing <NUM>.

Since air can flow into from the gap between the outer rotating body <NUM> and the sliding bearing <NUM>, rust may be generated in portions of the outer rotating body <NUM> and the inner rotating body <NUM> where the coating is not performed. Due to the rust, portions of the outer rotating body <NUM> and the inner rotating body <NUM>, which frequently comes into contact with the spring <NUM> (e.g., the pressure contact surface <NUM>, the abutting surface <NUM>, etc.), the sliding bearing <NUM> and the like are worn, and the life of the pulley structure <NUM> may be shortened. Therefore, a grease containing a rust inhibitor is sealed in the spring accommodation space <NUM> of the pulley structure <NUM>.

The grease is pasty at normal temperature and contains a base oil which is a rust inhibitor and a thickener that increases the consistency (hardness) of the base oil. The base oil is, for example, an ester oil (synthetic oil). As the thickener, for example, use can be made of a urea compound having excellent heat resistance. In order to sufficiently exert the lubrication state while maintaining the condition of the grease, the grease has a consistency comparable to JIS classification No. <NUM> to No. <NUM> at <NUM> (the test method is in accordance with JIS K <NUM>: <NUM>). The content of the thickener is preferably <NUM> to <NUM> mass% based on the total amount of the grease. The grease preferably has a kinematic viscosity of approximately <NUM><NUM>/s at <NUM> (the test method is in accordance with ASTM D <NUM>-<NUM>: <NUM>). The grease preferably has a specific gravity of approximately <NUM>. Although not illustrated in <FIG>, the grease is diffused over the entire surfaces forming the spring accommodation space <NUM>. The grease is also sealed inside the rolling bearing <NUM>.

Here, the grease is applied to the facing surface <NUM> of the inner rotating body <NUM> in a state in which the pulley structure <NUM> is not yet operated once such that the grease is likely to be diffused over the entire surfaces of the outer rotating body <NUM> and the inner rotating body <NUM>, forming the spring accommodation space <NUM>. Details will be described later.

The spring <NUM> is a torsion coil spring formed by spirally winding a spring wire. As the spring wire material of the spring <NUM>, for example, an oil-tempered wire for a spring (in accordance with JIS G <NUM>: <NUM>) can be used. The spring <NUM> is wound leftward (counterclockwise from the front end toward the rear end). The spring <NUM> has a substantially constant diameter over the entire length in a state in which the outer rotating body <NUM> and the inner rotating body <NUM> are not rotating. The spring <NUM> is interposed between the rear surface of the connection portion <NUM> of the inner rotating body <NUM> and the front surface of the rolling bearing , and thus, is accommodated in the spring accommodation space <NUM> in a state slightly compressed in the axial direction. The spring wire of the spring <NUM> has a rectangular cross-sectional shape, for example. An outer circumferential surface <NUM> and an inner circumferential surface <NUM> of the spring <NUM> are substantially parallel to the rotation axis R of the outer rotating body <NUM>. In a state where the outer rotating body <NUM> and the inner rotating body <NUM> are not rotating, the spring <NUM> has: a rear end side region <NUM> in which the outer circumferential surface <NUM> comes into contact with the pressure contact surface <NUM> of the outer rotating body <NUM>, in a rear end portion; and a front end side region <NUM> in which the inner circumferential surface <NUM> comes into contact with the contact surface <NUM> of the inner rotating body <NUM>, in a front end portion.

The rear end side region <NUM> is a region of one round or more (<NUM>° or more around the rotation axis) from the rear end of the spring <NUM>. In a state where the outer rotating body <NUM> and the inner rotating body <NUM> are not rotating, the rear end side region <NUM> is accommodated in the spring accommodation space <NUM> in a state where its diameter is slightly reduced. The outer circumferential surface <NUM> of the rear end side region <NUM> is pressed against the pressure contact surface <NUM> by the self-elastic-restoring force in the radial direction of the spring <NUM> (see <FIG> and <FIG>).

The front end side region <NUM> is a region of one round or more (<NUM>° or more around the rotation axis) from the front end of the spring <NUM>. In a state where the outer rotating body <NUM> and the inner rotating body <NUM> are not rotating, the front end side region <NUM> is accommodated in the spring accommodation space <NUM> in a state where the diameter thereof slightly expands. The inner circumferential surface <NUM> of the front end side region <NUM> is pressed against the contact surface <NUM> (see <FIG> and <FIG>). In addition, the front end side region <NUM> is composed of three portions. That is, as illustrated in <FIG>, the front end side region <NUM> includes: a first portion <NUM> on the front end side (the same direction as the arrow in <FIG>) of the spring <NUM> with respect to the projection <NUM> of the inner rotating body <NUM> in the circumferential direction; a second portion <NUM> facing to the projection <NUM> in the radial direction; and a third portion <NUM> on the rear end side (the direction opposite to the arrow in <FIG>) of the second portion <NUM>. In <FIG>, the portion of the spring <NUM> sandwiched by the two-dot chain lines is the second portion <NUM>. A front end surface <NUM> that faces the end surface <NUM> of the inner rotating body <NUM> in the circumferential direction is formed at the front end portion of the first portion <NUM>.

Next, the behavior of the pulley structure <NUM> will be described. First, the case where the rotational speed of the outer rotating body <NUM> becomes higher than the rotational speed of the inner rotating body <NUM> (i.e., the case where the outer rotating body <NUM> accelerates) will be described. The arrow directions in <FIG> are defined as a forward direction.

First, the outer rotating body <NUM> starts rotating relatively with respect to the inner rotating body <NUM> in the forward direction. Here, since the outer circumferential surface <NUM> of the rear end side region <NUM> of the spring <NUM> is pressed against the pressure contact surface <NUM> of the outer rotating body <NUM> (see <FIG>), with the relative rotation of the outer rotating body <NUM>, the rear end side region <NUM> of the spring <NUM> moves together with the pressure contact surface <NUM> towards the forward direction and rotates in the forward direction relatively with respect to the inner rotating body <NUM>. Accordingly, the spring <NUM> undergoes a torsional deformation in the diameter expansion direction (hereinafter, simply referred to as diameter expansion deformation). The pressure contact force of the rear end side region <NUM> of the spring <NUM> against the pressure contact surface <NUM> increases as the torsional angle of the spring <NUM> in the diameter expansion direction increases.

When the torsional angle of the spring <NUM> in the diameter expansion direction is less than a predetermined angle (e.g., <NUM>°), the largest torsional stress is generated in the second portion <NUM> of the front end side region <NUM> of the spring <NUM>, and the second portion <NUM> is most likely to undergo a diameter expansion deformation. Accordingly, first, the inner circumferential surface <NUM> of the second portion <NUM> is separated from the contact surface <NUM> due to the diameter expansion deformation when the torsional angle of the spring <NUM> in the diameter expansion direction increases. The outer circumferential surface of the second portion <NUM> abuts against the projection <NUM> and the diameter expansion deformation of the second portion <NUM> is restricted at substantially the same time when the second portion <NUM> is separated from the contact surface <NUM> or at the time when the torsional angle of the spring <NUM> in the diameter expansion direction further increases.

The pressure contact force of the third portion <NUM> with respect to the contact surface <NUM> becomes substantially zero at the same time when the second portion <NUM> abuts against the projection <NUM>, or at the time when the torsional angle of the spring <NUM> in the diameter expansion direction further increases. Furthermore, the third portion <NUM> is separated from the contact surface <NUM> due to diameter expansion deformation when the torsional angle further increases. At this time, the diameter expansion deformation of the front end side region <NUM> of the spring <NUM> is restricted by the projection <NUM>, and the front end side region <NUM> is maintained in an arc shape, that is, a shape that is easily slidable with respect to the projection <NUM>. Therefore, when the torsional angle further increases and the torsional torque acting on the spring <NUM> increases, the front end side region <NUM> slides in the circumferential direction with respect to the projection <NUM> and the contact surface <NUM> against the pressure contact force of the second portion <NUM> against the projection <NUM> and the pressure contact force of the first portion <NUM> against the contact surface <NUM>. In addition, as the front end surface <NUM> of the spring <NUM> abuts against the end surface <NUM> to press against the end surface <NUM>, torque can be reliably transmitted between the outer rotating body <NUM> and the inner rotating body <NUM>.

When the torsional angle of the spring <NUM> in the diameter expansion direction further increases, a portion between the front end side region <NUM> and the rear end side region <NUM> of the spring <NUM> increases in diameter. When the torsional angle reaches, for example, approximately <NUM>°, a part of the outer circumferential surface <NUM> of the diameter-expanded spring <NUM> abuts against the abutting surface <NUM> of the outer rotating body <NUM>, and the diameter expansion of the spring <NUM> is completely restricted, and the outer rotating body <NUM> and the inner rotating body <NUM> rotate integrally.

Next, the case where the rotational speed of the outer rotating body <NUM> is smaller than the rotational speed of the inner rotating body <NUM> (i.e., when the outer rotating body <NUM> decelerates) will be described. In this case, the outer rotating body <NUM> rotates in the opposite direction (opposite to the direction of the arrows in <FIG>) relatively with respect to the inner rotating body <NUM>. With the relative rotation of the outer rotating body <NUM>, the rear end side region <NUM> of the spring <NUM> moves together with the pressure contact surface <NUM> and rotates relative with respect to the inner rotating body <NUM>. Accordingly, the spring <NUM> undergoes a torsional deformation in the diameter reduction direction (hereinafter, simply referred to as "diameter reduction deformation").

When the torsional angle of the spring <NUM> in the diameter reduction direction is smaller than a predetermined angle (e.g., <NUM>°), the pressure contact force of the rear end side region <NUM> with respect to the pressure contact surface <NUM> slightly decreases as compared to the case where the torsional angle is zero, but the rear end side region <NUM> presses against the pressure contact surface <NUM>. Furthermore, the pressure contact force of the front end side region <NUM> with respect to the contact surface <NUM> is slightly increased as compared to the case where the torsional angle is zero. When the torsional angle of the spring <NUM> in the diameter reduction direction further increases, the pressure contact force of the rear end side region <NUM> with respect to the pressure contact surface <NUM> becomes substantially zero, and the rear end side region <NUM> slides in the circumferential direction of the outer rotating body <NUM> with respect to the pressure contact surface <NUM>. Therefore, no torque is transmitted between the outer rotating body <NUM> and the inner rotating body <NUM>. In this way, the spring <NUM> transmits or blocks torque between the outer rotating body <NUM> and the inner rotating body <NUM>.

Next, a method for manufacturing the pulley structure <NUM> will be described with reference to <FIG>.

First, the spring <NUM> is press-fitted into the inner rotating body <NUM> (see (a) of <FIG>) from the rear (see (b) of <FIG>). Next, the sliding bearing <NUM> is mounted on the front end portion of the inner rotating body <NUM> (see (c) of <FIG>), and the outer rotating body <NUM> is mounted on the inner rotating body <NUM> from the rear (see (d) of <FIG>).

In this state, grease is applied to the facing surface <NUM> of the inner rotating body <NUM>. For applying the grease, for example, a dispenser <NUM> is used. As illustrated in (e) of <FIG>, the dispenser <NUM> includes a main body <NUM> and a nozzle <NUM> extending from the main body <NUM>, and is configured to be able to apply the grease to an object by measuring the grease and discharging the measured grease from the nozzle <NUM>. The nozzle <NUM> has a diameter that can be inserted between the facing surface <NUM> of the inner rotating body <NUM> and the inner circumferential surface <NUM> of the spring <NUM>, and a discharge port <NUM> from which the grease is discharged is formed at its tip end portion. The discharge port <NUM> is inclined obliquely with respect to the direction in which the nozzle <NUM> extends.

First, the grease is weighed by using the dispenser <NUM>. The amount of the grease required is the minimum amount necessary for forming an oil film on the entire surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> on which the coating is not applied, among the surfaces forming the spring accommodation space <NUM>. For example, in the present embodiment, the amount of the grease is approximately <NUM> (volume is approximately <NUM><NUM>).

Next, as illustrated in (e) of <FIG>, the nozzle <NUM> of the dispenser <NUM> is inserted between the facing surface <NUM> of the inner rotating body and the inner circumferential surface <NUM> of the spring <NUM> from the rear of the inner rotating body <NUM>. Here, the press-fit surface <NUM> is in the rear of the facing surface <NUM>, but the nozzle <NUM> can be easily inserted since the diameter of the press-fit surface <NUM> is smaller than the diameter of the facing surface <NUM>. Next, in order to prevent the inner rotating body <NUM> from being damaged, the tip end of the nozzle <NUM> is stopped at a position in the rear (e.g., by <NUM>) of the inclined surface between the facing surface <NUM> and the contact surface <NUM>. Next, at this stop position as a starting position, the discharge port <NUM> is made to face to the facing surface <NUM> of the inner rotating body <NUM> in the radial direction. Then, while the nozzle <NUM> is moved from the front side to the rear side and retreated to near the press-fit surface <NUM>, and the grease <NUM> is extruded substantially uniformly and is applied to the facing surface <NUM>. Accordingly, the grease <NUM> is in a state of extending long in the front-rear direction (see <FIG>). The grease <NUM> is not applied to portions other than the facing surface <NUM>, such as the press-fit surface <NUM>. Next, the inner rotating body is slightly rotated, the nozzle <NUM> is inserted again, and the grease <NUM> is discharged while the nozzle <NUM> is retracted. The above operation is repeated a plurality of times to apply the grease <NUM> to the facing surface <NUM>.

Next, the rolling bearing <NUM> is press-fitted between the rear end portion of the outer rotating body <NUM> and the rear end portion of the inner rotating body <NUM> (see (f) of <FIG>). At this time, the assembly of the pulley structure is once completed except for mounting of the end cap <NUM> and the like. The pulley structure <NUM> (see (f) of <FIG> and <FIG>) at the time when the assembly is once completed corresponds to a pulley structure of the present invention in a state in which it is not yet operated once. The difference between the pulley structure <NUM>, which is a finished product at the time of shipment, and the pulley structure <NUM> that is not yet operated once, is whether or not the end cap <NUM> is mounted, and is whether it is in a state in which the grease is diffused on the surfaces forming the spring accommodation space <NUM> or in a state in which the grease is applied to the facing surface <NUM> of the inner rotating body <NUM>.

As illustrated in <FIG>, the grease <NUM> is in a state of being applied to the facing surface <NUM> of the inner rotating body <NUM> in a state in which the pulley structure <NUM> is not yet operated once immediately after assembly, that is, in a state in which it is not yet connected to the drive shaft <NUM> of the alternator <NUM>. In other words, the grease <NUM> strongly contacts the facing surface <NUM> as compared to the case where the grease <NUM> is simply charged into the spring accommodation space <NUM>. Since the grease <NUM> is applied while moving the nozzle <NUM> in the front-rear direction as described above, the grease <NUM> extends long in the front-rear direction and is disposed discontinuously in the circumferential direction. The amount of the grease <NUM> is a minimum amount necessary for forming an oil film on the entire surfaces on which the coating is not applied among the surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> forming the spring accommodation space <NUM>, and is, for example, approximately <NUM> (volume is approximately <NUM><NUM>). The thickness of the grease <NUM> on the facing surface <NUM> is preferably <NUM> or less. The thickness of the grease <NUM> on the facing surface <NUM> is more preferably approximately <NUM> to <NUM>. The area of the grease <NUM> adhering to the facing surface <NUM> is preferably <NUM>% or more of the area of the facing surface <NUM>. The area of the grease <NUM> adhering to the facing surface <NUM> is more preferably approximately <NUM>% to <NUM>% of the area of the facing surface <NUM>. The grease <NUM> is applied only to the facing surface <NUM> of the surfaces forming the spring accommodation space <NUM>, and is not applied to the other surfaces.

Next, in a manufacturer and the like of the alternator <NUM>, the pulley structure <NUM> is connected to the drive shaft <NUM> of the alternator <NUM>. Next, a completion inspection of the alternator <NUM> is performed, and at the same time, the grease <NUM> is diffused into the surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> forming the spring accommodation space <NUM>. Specifically, for example, as illustrated in <FIG>, a tester 100a having a configuration equivalent to that of the belt power-transmission mechanism <NUM> (see <FIG>) is used, the belt B is wound around the pulley structure <NUM> and the other pulleys including the pulley 101a connected to the crankshaft 111a of an engine 110a and the like, and the engine initiation and stop are repeated under the same operating conditions as the engine initiation test described later, to operate the pulley structure <NUM>. The number of times of initiating the engine is, for example, five times. Accordingly, the temperature of the spring accommodation space <NUM> is raised due to the heat generated with the rotation of the pulley structure <NUM> and the heat generated by the power generation of the alternator <NUM>. For example, the surface temperature of the facing surface <NUM> increases to about <NUM> in the completion inspection. The temperature of the spring accommodation space <NUM> is raised and the shear heat is generated by friction between the grease <NUM> or between the grease <NUM> and the facing surface <NUM> so that the temperature of the grease <NUM> applied to the facing surface <NUM> is raised, the viscosity of the grease <NUM> decreases to facilitate flowing. Since the centrifugal force acts on the grease <NUM> by the rotation of the inner rotating body <NUM>, the grease <NUM> is scattered radially outward and is diffused to the pressure contact surface <NUM> of the outer rotating body <NUM> and the like. Apart of the grease <NUM> also contacts the spring <NUM>, and is also diffused in the front-rear direction, for example, by flowing along the spring wire. In this way, the grease <NUM> is diffused into the entire surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> forming the spring accommodation space <NUM>. The grease is also diffused into the gap between the sliding bearing <NUM> and the outer rotating body <NUM>, but hardly leaks forward from the gap.

Finally, the end cap <NUM> is mounted on the front end portion of the outer rotating body <NUM>. Accordingly, the pulley structure <NUM> is completed (see (g) of <FIG>).

Next, specific examples of the present invention will be described. The inventors of the present invention conducted tests for verifying the effects of the present invention by using the specimens of the pulley structures of Example <NUM> and Comparative Examples <NUM> to <NUM> shown in Table <NUM>.

The specimen of the pulley structure in Example <NUM> is a pulley structure 10d illustrated in (d) of <FIG>, and is the same as the pulley structure <NUM> including retention position and state of the grease. The grease 200d is applied to the facing surface <NUM> of the inner rotating body <NUM> in a flat shape. The amount of the grease 200d is approximately <NUM> (volume of approximately <NUM><NUM>). The retention position of the grease 200d before assembling the specimen to the alternator is a portion ranging from substantially the center to the rear end portion of the facing surface <NUM> of the inner rotating body <NUM> in the front-rear direction. The same applies to Example <NUM> described later. The thickness of the grease 200d on the facing surface <NUM> is approximately <NUM>, and the area of the grease 200d adhering to the facing surface <NUM> is approximately <NUM>% of the area of the facing surface <NUM>.

The specimen of the pulley structure in Example <NUM> is a pulley structure 10e illustrated in (d) of <FIG> in which the grease 200e is applied to the facing surface <NUM> of the inner rotating body <NUM>. The thickness of the grease 200e on the facing surface <NUM> is <NUM> to <NUM>, and the area of the grease 200e adhering to the facing surface <NUM> is approximately <NUM>% of the area of the facing surface <NUM>.

The specimen of the pulley structure in Comparative Example <NUM> is a pulley structure 10a illustrated in (a) of <FIG>, and has the same configuration as the pulley structure <NUM> except for the retention position and the state of the grease. In the spring accommodation space <NUM>, approximately <NUM> of the grease 200a is put in a lump state. The same applies to Comparative Examples <NUM> and <NUM> described later. The retention position of the grease 200a is substantially the center of the facing surface <NUM> of the inner rotating body <NUM> in the front-rear direction.

The specimen of the pulley structure in Comparative Example <NUM> is a pulley structure 10b illustrated in (b) of <FIG>, and the grease 200b is put into the spring accommodation space <NUM> in a lump state. The retention position of the grease 200b is a rear end portion of the facing surface <NUM> of the inner rotating body <NUM>.

The specimen of the pulley structure in Comparative Example <NUM> is a pulley structure 10c illustrated in (c) of <FIG>, and the grease 200c is put into the spring accommodation space <NUM> in a lump state. The retention position of the grease 200c is substantially the center of the outer circumferential surface <NUM> of the spring <NUM> in the front-rear direction.

Next, an engine initiation test for verifying the effect of the present invention will be described. The inventors of the present invention conducted an engine initiation test to confirm the adhesion state of the rust inhibitor to the object portions of the outer rotating body <NUM> and the inner rotating body <NUM> (portions on which the coating is not applied and the rust inhibitor is necessary) forming the spring accommodation space <NUM>.

First, an outline of the engine initiation test will be described. The specimens of the pulley structure to be evaluated are five types of the pulley structures 10a to 10e described above. The engine initiation test of each specimen was performed at a predetermined number of times of initiating the engine (number of times from the initiating to the stopping), and then each specimen was disassembled to visually confirm the presence or absence of the rust inhibitor adhering to object portions, and the presence or absence of adhesion of the rust inhibitor was evaluated based on the evaluation criteria described later. The specific object portions are the portions shown in Table <NUM> and <FIG>, that is, the bearing-interposing surface <NUM>, the pressure contact surface <NUM> and the abutting surface <NUM> of the outer rotating body <NUM>, the facing surface <NUM> of the inner rotating body <NUM>, and other portions. The other portions are portions other than the bearing-interposing surface <NUM>, the pressure contact surface <NUM>, the abutting surface <NUM>, and the facing surface <NUM> among the surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> forming the spring accommodation space <NUM>, and are portions where the coating is not applied.

Next, details of the engine initiation test will be described. For each specimen, an engine initiation test was performed by using an engine bench test machine having the same configuration as that of the belt power-transmission mechanism <NUM> (see <FIG>). The ambient temperature was adjusted such that the surface temperature of the facing surface <NUM> was approximately <NUM> when the number of times of initiating the engine was <NUM> times so as to be consistent with the surface temperature (approximately <NUM>) of the facing surface <NUM> of the inner rotating body <NUM> to be reached in the completion inspection of the alternator corresponds to five times of initiating the engine. The number of times of initiating the engine was set three types (<NUM> times, <NUM> times, <NUM> times) of, each specimen was prepared corresponding to each number of times of initiating the engine. The initiating and stopping of the engine are alternately repeated, and the test of the specimen was ended when the number of times of initiating the engine reaches a predetermined number of times. The tensile force of the belt was <NUM>,<NUM> N. One operating time of the engine (time from the initiating to the stopping) was set to <NUM> seconds. In addition, the ambient temperature was set and adjusted on the assumption of the same temperature as the actual vehicle. Further, the rotational speed of the crankshaft at each time of initiating the engine varies between <NUM> and <NUM>,<NUM> rpm. The maximum rotational speed of the drive shaft of the alternator and the inner rotating body <NUM> at this time reaches approximately <NUM>,<NUM> rpm. By the above test, the temperature of the spring accommodation space <NUM> is raised, the temperature of the grease is raised, and the viscosity is decreased. Further, since the centrifugal force acts on the grease by the rotation of the pulley structures 10a to 10e, the grease is diffused on the surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> forming the spring accommodation space <NUM>.

After completion of the test, the pulley structure was disassembled, and adhesion state of the rust inhibitor was visually confirmed for each object portion. The case where the rust inhibitor was adhered to the entire object portion, was considered as evaluation A (passed). The case where the rust inhibitor was not adhered to at least a part of the object portion, was considered as evaluation B (failed). The evaluation of portions other than the bearing-interposing surface <NUM>, the pressure contact surface <NUM>, the abutting surface <NUM>, and the facing surface <NUM> was performed only when the evaluations of these four portions were all A. Further, in each Example or Comparative Example, when the evaluation of all the portions was A, the test was ended.

The test results were as shown in Table <NUM>. In Examples <NUM> and <NUM> in which the grease <NUM> was applied to the facing surface <NUM> of the inner rotating body <NUM>, adhesion of the rust inhibitor was confirmed on all the object portions at the end of five times of initiating the engine. On the other hand, in Comparative Examples <NUM> to <NUM> in which the grease was put in a lump state, a place where the rust inhibitor was not adhered was recognized in the object portion. As a particularly significant tendency, in Comparative Examples <NUM> and <NUM> in which the lump of the grease is put to the facing surface <NUM>, the rust inhibitor tended to be less likely to reach the bearing-interposing surface <NUM> at the front end portion of the outer rotating body <NUM> farther from the facing surface <NUM>. Further, in Comparative Example <NUM> in which the lump of the grease was put to the outer circumferential surface <NUM> of the spring <NUM>, even when the initiating and the stopping of the engine were repeated <NUM> times, the rust inhibitor did not reach the facing surface <NUM> radially inward on the spring <NUM>. From the above results, it has been found that when the pulley structure is configured as in Examples <NUM> or <NUM>, the rust inhibitor can be adhered to all the object portions with a small number of times of initiating the engine.

A composite environmental cycle test (<NUM> hours per one cycle) in which salt water-spraying (in accordance with JIS K <NUM>-<NUM>-<NUM>) and drying was repeated was performed on the pulley structures in Examples <NUM>, <NUM> and Comparative Example <NUM>. First, an engine initiation test was carried out with <NUM> times of initiating the engine in new pulley structures having the same configuration as the pulley structures <NUM> (pulley structures 10d and 10e) in Examples <NUM> and <NUM>, and then the composite environmental cycle test was performed. As a result, even when the test of <NUM> cycles (<NUM>,<NUM> hours) was performed on the pulley structure, rust was not generated on the surfaces of the outer rotating body <NUM> and the inner rotating body <NUM> forming the spring accommodation space <NUM>. On the other hand, the same engine initiation test and composite environmental cycle test were performed on a pulley structure having the same configuration as that of the pulley structure 10a in Comparative Example <NUM>. As a result, an indication of rust generation was observed at <NUM> cycles (<NUM>,<NUM> hours) on the portion (bearing-interposing surface <NUM> and pressure contact surface <NUM>) to which the rust inhibitor was not adhered in Table <NUM>. In the case where the grease is not sealed in the spring accommodation space <NUM>, an indication of rust generation was observed in the entire uncoated region of the outer rotating body <NUM> and the inner rotating body <NUM> facing the spring accommodation space <NUM> at <NUM> cycles.

As described above, in a state before the pulley structure <NUM> is connected to the drive shaft <NUM> of the alternator, that is, in a state in which it is not yet operated once, the grease <NUM> is in a state of being applied to the facing surface <NUM> of the inner rotating body <NUM>. As a result, the contact area with the inner rotating body <NUM> becomes larger as compared to the case where the grease <NUM> is simply put into the spring accommodation space <NUM> in a lump state, so that the heat of the inner rotating body <NUM> is likely to be transferred to the grease <NUM> during the engine initiation test, the temperature of the grease <NUM> is likely to be raised and the viscosity is likely to decrease. Since the grease is applied to the facing surface <NUM> of the inner rotating body <NUM> disposed radially inward among the surfaces forming the spring accommodation space <NUM>, the grease is likely to spread over the inner rotating body <NUM> and the centrifugal force due to the rotation of the inner rotating body <NUM> acts on the grease <NUM>, so that the grease <NUM> is also likely to be diffused outward in the radial direction. Therefore, the rust inhibitor can be made to be easily diffused in the entire region facing the spring accommodation space <NUM>.

The thickness of the grease <NUM> on the facing surface <NUM> is <NUM> or less. Therefore, the heat of the inner rotating body <NUM> is likely to be transmitted to the entire grease <NUM>, and the viscosity of the grease <NUM> can be made to be easily lowered.

The area of the grease <NUM> adhering to the facing surface <NUM> is <NUM>% or more of the area of the facing surface <NUM>. That is, since the heat-transfer area of the grease <NUM> is large, the heat of the inner rotating body <NUM> is likely to be transferred to the grease <NUM>.

In addition, since the grease <NUM> extends in the front-rear direction, when the pulley structure <NUM> rotates, the grease <NUM> can be made to be easily diffused in the front-rear direction.

The grease <NUM> is applied only to the facing surface <NUM> of the inner rotating body <NUM>. Therefore, it is possible to efficiently diffuse the grease <NUM> into the spring accommodation space <NUM> by the rotation of the inner rotating body <NUM> while reducing the labor as compared to the case where the grease <NUM> is also applied to other places.

Furthermore, since the grease <NUM> is applied to the facing surface <NUM> of the inner rotating body <NUM>, the grease <NUM> is likely to be diffused on the entire surfaces forming the spring accommodation space <NUM>. Therefore, even in the case where the grease is not applied to the outer rotating body <NUM> of the pulley structure <NUM>, the grease <NUM> is spread to the front end portion of the outer rotating body <NUM> in which the sliding bearing <NUM> is disposed, and the generation of rust in the portion is suppressed, and the bearing function is maintained for a long period of time. Therefore, it is possible to prolong the life of the pulley structure while suppressing a decrease in production efficiency.

The sliding bearing <NUM> is formed of a resin composition containing polytetramethylene adipamide as a base resin, and the resin composition contains a reinforcing material containing aramid fibers. As a result, since wear resistance and strength of the sliding bearing <NUM> can be increased even in a relatively high temperature range, the bearing function can be maintained for a longer period of time.

When the pulley structure <NUM> is connected to the alternator <NUM> and rotates, large heat is generated with power generation due to driving of the alternator <NUM>, and is transmitted to the pulley structure <NUM>. Therefore, the temperature of the grease <NUM> can be sufficiently raised.

After applying of the grease <NUM>, the pulley structure <NUM> is connected to the alternator <NUM>, and the power of the engine 110a is transmitted to the pulley structure <NUM> via the belt B to operate the pulley structure <NUM>. As a result, the grease can be diffused to the surfaces forming the spring accommodation space <NUM> due to the temperature rise of the spring accommodation space <NUM> with the rotation operation of the pulley structure <NUM>, the centrifugal force acting on the grease <NUM> by the rotation of the inner rotating body <NUM> and the like.

After the spring <NUM> is mounted on the inner rotating body <NUM>, the nozzle <NUM> is inserted into the gap between the torsion coil spring <NUM> and the inner rotating body <NUM>, and the grease <NUM> is applied to the facing surface. Accordingly, it is possible to prevent the grease <NUM> from adhering to the spring <NUM>.

Claim 1:
A pulley structure (<NUM>) to be connected to an accessory machine (<NUM>) of an engine and to which power of the engine is to be transmitted via a belt (B), the pulley structure comprising:
a cylindrical outer rotating body (<NUM>) around which the belt is to be wound;
an inner rotating body (<NUM>) provided radially inward on the outer rotating body and relatively rotatable with respect to the outer rotating body; and
a torsion coil spring (<NUM>) disposed in a spring accommodation space (<NUM>) formed between the outer rotating body and the inner rotating body, wherein
the pulley structure is in an assembled state, but has not yet been operated once,
characterized in that in said state where the pulley structure has not yet been operated once, a grease (<NUM>) containing a rust inhibitor is in a state of being applied to a facing surface (<NUM>) of the inner rotating body, facing an inner circumferential surface (<NUM>) of the torsion coil spring; wherein
the grease is applied only to the facing surface of the inner rotating body among surfaces forming the spring accommodation space.