Pulley structure

Abstract

To provide a pulley structure capable of preventing displacement of a pulley to one end side with respect to a hub, even when impact force is applied to the pulley from the other end side to one end side in a state of being connected to a drive shaft of an auxiliary machine positioned at one end side.SOLUTION: A pulley structure 1 includes: a cylindrical pulley 2 on which a belt Y is wound; a hub 3 fixed to a drive shaft S of an alternator 101; and a rolling bearing 7 having an outer ring 71, an inner ring 72 and a ball 73 separately held between the outer ring 71 and the inner ring 72, and press-fitted between an inner peripheral surface 2f of one end portion of the pulley 2 and an outer peripheral surface of one end portion of the hub 3, and the pulley 2 is relatively rotatable to the hub 3. The pulley 2 has a first contact surface B kept into contact with the other end surface 71a of the outer ring 71 of the rolling bearing 7, and the hub 3 has a first hub 31 having a second contact surface A kept into contact with the other end surface 72a of the inner ring 72, and a second hub 32 having a third contact surface C kept into contact with one end surface 72d of the inner ring 72.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a pulley structure connected to a drive shaft of an accessory such as an alternator of an automobile engine.

Background Art

[0002] Conventionally, for example, a pulley structure (accessory pulley) connected to a drive shaft of an alternator (accessory) of an automobile engine is usually configured as follows to position the pulley in the rotational axis direction (hereinafter, the axial direction).

[0003] (A) Pulley structure and alternator (accessory) As shown in FIG. 1, the pulley structure (accessory pulley) includes a cylindrical pulley around which a belt is wound, a hub provided inside the pulley so as to be relatively rotatable with respect to the pulley and fixed to the drive shaft of the accessory, and a rolling bearing interposed between one end of the pulley and one end of the hub.

[0004] As shown in FIG. 2, the alternator is located on one end side of the pulley structure, and is rotatably supported via a housing and a bearing B (rolling bearing for the drive shaft) located on the other end side of the housing, and includes a drive shaft S protruding from the housing to the outside on the other end side. This bearing B is axially positioned in a manner of being sandwiched from both axial sides by a step portion of the drive shaft S that abuts against one end face of the inner ring and an inward edge portion of the housing that abuts against the other end face of the outer ring.

[0005] The hub is fixed to the drive shaft S by screwing a female screw portion formed on the inner peripheral surface thereof onto a male screw portion formed on the outer peripheral surface of the tip of the drive shaft S. At this time, by abutting one end face of the hub against the other end face of the inner ring of the bearing B of the alternator, the hub (and thus the pulley) is axially positioned with respect to the alternator (drive shaft S) (see FIG. .

[0006] (B) Main parts of the pulley structure (pulley, rolling bearing, hub) As shown in Figures 1 and 3, the rolling bearing is interposed by being press-fitted between one end of the pulley and one end of the hub. The hub is configured to have a contact surface (hereinafter referred to as contact surface A) that abuts against the other end face of the inner ring of the rolling bearing, as shown in Figure 3, in order to facilitate the axial positioning of the rolling bearing (in the example in Figure 1, contact surface A is formed by creating an outwardly protruding stepped portion on the hub (cylindrical body)). To facilitate axial positioning by the rolling bearing, the pulley is configured to have a contact surface (hereinafter referred to as contact surface B) that abuts against the other end face of the outer ring of the rolling bearing, as shown in Figure 3 (in the example in Figure 1, contact surface B is formed by creating an inwardly protruding annular plate portion on the pulley). When pressing in the rolling bearing, the pulley and hub are more easily positioned axially by abutting the rolling bearing against contact surfaces A and B (see Figure 3). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2013 / 077422 [Patent Document 2] Japanese Patent Publication No. 2008-528906 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Incidentally, manufacturers of alternators (auxiliary components) sometimes perform a final inspection of the alternator by connecting the pulley structure, which is assembled to the drive shaft of the alternator (as shown in Figure 2), except for the attachment of the end caps. In this final inspection process, as shown in Figure 4, if an impact force is applied to the pulley from one end to the other end, such as when the other end face of the pulley is struck or when the alternator with the pulley structure attached is placed on the floor or the like with the other end face of the pulley facing directly downwards, the pulley structure may interfere with the alternator (auxiliary component) in the following ways, as shown in a) and b).

[0009] a) In a pulley structure as shown in Figure 1, in which the pulley has a contact surface (contact surface B) that abuts against the other end face of the outer ring of the rolling bearing, the press-fit surface between the hub and the rolling bearing may come loose due to impact (the press-fit surface becoming a sliding surface), causing the pulley and rolling bearing assembly to shift position (relative movement) toward one end relative to the hub, which may interfere with the alternator (auxiliary equipment) (see Figure 4). b) Although not shown in the diagram, in a pulley structure in which the contact surface B is not present on the pulley, an impact may cause the press-fit surface between the pulley and the rolling bearing to come loose (the press-fit surface becoming a sliding surface), causing only the pulley to shift position (relative movement) toward one end relative to the hub, which may interfere with the alternator (auxiliary equipment).

[0010] In any case, if the system continues to operate without the interference being noticed, it may lead to malfunctions such as abnormal noises, poor rotation, or damage to rolling bearings. Therefore, it is necessary to address the problem that an impact force on the other end of the pulley causes the pulley to shift relative to the hub towards one end, interfering with auxiliary equipment.

[0011] In this regard, Patent Documents 1 and 2 disclose a method for adjusting the axial length of the hub (positioning the pulley in the axial direction) by attaching a spacer member (corresponding to a second hub) to one end of the hub, so that the main body of the pulley structure can be shared between different vehicle models (see Table 1 below).

[0012] [Table 1]

[0013] However, the configurations in Patent Documents 1 and 2 do not have a contact surface B on the pulley, raising concerns that the pulley may shift axially. They do not recognize the problem of the present invention (the pulley shifting to one end relative to the hub due to an impact force on the other end of the pulley), and they do not mention the axial configuration (contact surface) between the pulley, rolling bearing, and hub.

[0014] Therefore, the object of the present invention is to provide a pulley structure that can prevent the pulley from shifting relative to the hub toward one end even when an impact force is applied to the pulley from the other end toward one end while it is connected to the drive shaft of an auxiliary device located at one end. [Means for solving the problem]

[0015] To solve the above problems, the present invention provides A cylindrical pulley around which the belt is wrapped, A hub provided on the inner circumference side of the pulley and fixed to the drive shaft of an auxiliary device located at one end, A pulley structure comprising an outer ring that abuts against the inner circumferential surface of one end of the pulley, an inner ring that abuts against the outer circumferential surface of one end of the hub, and a rolling bearing press-fitted between the inner circumferential surface of one end of the pulley and the outer circumferential surface of one end of the hub, wherein the pulley is rotatable relative to the hub, The pulley has a first contact surface that contacts the other end surface of the outer ring of the rolling bearing, The hub is characterized by having a first hub having a second contact surface that contacts the other end surface of the inner ring, and a second hub having a third contact surface that contacts one end surface of the inner ring.

[0016] According to the above configuration, the rolling bearing is press-fitted between the inner circumferential surface of one end of the pulley and the outer circumferential surface of one end of the hub. By sandwiching the rolling bearing from both axial sides between the second contact surface of the first hub and the third contact surface of the second hub, the rolling bearing can be positioned in the axial direction while being sandwiched between the first contact surface of the pulley and the third contact surface of the second hub. As a result, even if an impact force is applied to the other end face of the pulley while the hub of the pulley structure is connected to the drive shaft of an auxiliary device such as an alternator, this impact force (external force) will act directly on the drive shaft side of the auxiliary device, which is fixed to the second hub, via the pulley, rolling bearing, and second hub, which are in axial contact with each other. That is, according to the above configuration, even when an impact force from the other end side to the one end side acts on the pulley while the pulley structure is connected to the drive shaft of the auxiliary machine located on the one end side, it is possible to prevent the pulley from being displaced to the one end side with respect to the hub.

[0017] Further, the present invention relates to the above pulley structure, where the first hub has a first hub outer peripheral surface that abuts against the inner peripheral surface of the other end portion of the inner ring, and the second hub may have a second hub outer peripheral surface that abuts against the inner peripheral surface of the one end portion of the inner ring.

[0018] According to the above configuration, when an impact force from the other end side to the one end side acts on the pulley, the impact force can be dispersed to both the first hub and the second hub.

Effect of the Invention

[0019] According to the present invention, it is possible to provide a pulley structure that can prevent the pulley from being displaced to the one end side with respect to the hub even when an impact force from the other end side to the one end side acts on the pulley while the pulley is connected to the drive shaft of the auxiliary machine located on the one end side.

Brief Description of the Drawings

[0020] [Figure 1] It is a cross-sectional view taken along a direction passing through the rotation axis of the pulley structure and parallel to the rotation axis, showing the pulley structure according to the prior art (Comparative Example 1). [Figure 2] It is a cross-sectional view taken along a direction passing through the rotation axis of the pulley structure and parallel to the rotation axis, showing a state where the pulley structure according to the prior art (Comparative Example 1) is connected to the alternator. [Figure 3] It is an enlarged view of part A in FIG. 1. [Figure 4] It is an explanatory diagram of a mode in which the assembly of the pulley and the rolling bearing is displaced (relatively moved) to the one end side with respect to the hub and interferes with the alternator. [Figure 5]This is a cross-sectional view showing the pulley structure according to this embodiment (Example 1), passing through the axis of rotation of the pulley structure and in a direction parallel to the axis of rotation. [Figure 6] This is an enlarged view of section A in Figure 5, illustrating a hub where one end face of the first hub and the other end face of the second hub are facing each other in an axially contacted state. [Figure 7] This is a cross-sectional view showing the pulley structure according to this embodiment (Example 1) connected to an alternator, passing through the rotation axis of the pulley structure and in a direction parallel to the rotation axis. [Figure 8] This is an explanatory diagram of a hub in which one end face of the first hub and the other end face of the second hub are facing each other while being separated in the axial direction. [Modes for carrying out the invention]

[0021] (Structure of pulley structure 1) The pulley structure 1 according to an embodiment of the present invention, shown in Figure 5, is attached, for example, to the drive shaft S of an alternator 101 in an auxiliary drive system of an automobile (see Figure 7). The auxiliary drive system includes a drive pulley attached to the crankshaft of the engine, a driven pulley including the pulley structure 1 that drives an auxiliary device such as an alternator, and a belt Y wound around these. The rotation of the crankshaft is transmitted to the driven pulley including the pulley structure 1 via the belt Y, thereby driving the auxiliary device such as the alternator. As the rotational speed of the crankshaft fluctuates in accordance with the combustion of the engine, the travel speed of the belt Y also fluctuates.

[0022] As shown in Figures 5 and 6, the pulley structure 1 includes a pulley 2, a hub 3, a torsion coil spring 4 (hereinafter simply referred to as "spring 4"), end caps 5 positioned at the other ends of the pulley 2 and hub 3, and a pair of bearings 6 and 7 consisting of a sliding bearing 6 and a rolling bearing 7.

[0023] Pulley 2 and hub 3 are both substantially cylindrical and share the same axis of rotation X (the axis of rotation of pulley structure 1, hereinafter simply referred to as "axis of rotation X"). The axis of rotation X extends along the left-right direction (axial direction) in Figure 5. In the following, the right side of Figure 5 will be referred to as one end in the axial direction, and the left side of Figure 5 will be referred to as the other end in the axial direction.

[0024] (Pulley 2) The pulley 2 is located on the outer circumference of the hub 3 and is rotatable relative to the hub 3. Belt Y is wrapped around the outer surface of pulley 2.

[0025] The inner diameter of pulley 2 increases in three stages from one end to the other. Specifically, the inner circumferential surface of pulley 2 at the smallest inner diameter portion is called the contact surface 2a, and the inner circumferential surface of pulley 2 at the second smallest inner diameter portion is called the annular surface 2b. The inner circumferential surface of pulley 2 at the largest inner diameter portion is called the inner circumferential surface 2c, which is radially opposite to the sliding bearing 6 and extends axially. The inner diameter of pulley 2 at the contact surface 2a is smaller than the inner diameter of the outer cylinder portion 31b of the hub 3 (first hub 31). The inner diameter of pulley 2 at the annular surface 2b is the same as or larger than the inner diameter of the outer cylinder portion 31b of the hub 3.

[0026] As shown in Figure 5, the other end side surface 2d of pulley 2 protrudes beyond the other end surface 31d of hub 3 (first hub 31).

[0027] Furthermore, a ring-shaped plate portion 2e is formed on the contact surface 2a of the pulley 2, projecting radially inward. The side surface at one end of this ring-shaped plate portion 2e becomes a first contact surface B that abuts against the other end surface 71a of the outer ring 71 of the rolling bearing 7.

[0028] (Hub 3) The hub 3 is located on the inner circumference side of the pulley 2 and is rotatable relative to the pulley 2. As shown in Figures 5 to 7, the hub 3 has a first hub 31 located at the other end and a second hub 32 located at one end in the axial direction. The first hub 31 is fixed to the drive shaft S of the alternator 101 located at one end by screwing it in (details will be described later).

[0029] (Hub 1, 31) The first hub 31 has a cylindrical body 31a with a screw groove formed on its inner circumferential surface into which the drive shaft S of the alternator is screwed, an outer cylindrical portion 31b positioned outside the other end of the cylindrical body 31a, an annular plate portion 31c connecting the other end of the cylindrical body 31a and the other end of the outer cylindrical portion 31b, and a stepped portion 31e formed on the outer circumferential surface of the cylindrical body 31a. Furthermore, the outer circumferential surface of one end of the cylindrical body 31a of the first hub 31 is called the first hub outer circumferential surface 31f, which abuts against the inner circumferential surface 72b of the other end of the inner ring 72.

[0030] The side surface of one end of the stepped portion 31e of the first hub 31 becomes a second contact surface A that abuts in the axial direction against the other end surface 72a of the inner ring 72 of the rolling bearing 7.

[0031] (Second Hub 32) The second hub 32 has a stepped cylindrical shape in which its outer diameter increases in two stages from one end to the other (divided axially into a small diameter portion 321 and a large diameter portion 322).

[0032] The small-diameter portion 321 has an outer diameter that is slightly larger than the inner diameter of the rolling bearing 7 (inner ring 72), and is the portion that is press-fitted onto the inner circumferential surface 72c of one end of the rolling bearing 7 (inner ring 72) (by press-fitting the small-diameter portion 321 of the second hub 32 onto the rolling bearing 7, the second hub 32 is treated as part of the pulley structure 1). The outer circumferential surface of the small-diameter portion 321 is called the outer circumferential surface 32a of the second hub that abuts against the inner circumferential surface 72c of one end of the inner ring 72.

[0033] The side surface of the other end of the large-diameter portion 322 (an annular surface that is exposed at the edge of the small-diameter portion 321 and extends radially) becomes a third contact surface C that abuts in the axial direction against one end surface 72d of the inner ring 72 of the rolling bearing 7.

[0034] (Relationship between Hub 1 31 and Hub 2 32) With the second hub 32 (small diameter portion 321) pressed into the rolling bearing 7, the first hub 31 and the second hub 32 are positioned such that one end face 31g of the first hub 31 and the other end face 32b of the second hub 32 face each other in the axial direction. Here, as shown in Figure 6, with the second hub 32 (small diameter portion 321) pressed into the rolling bearing 7, one end face 31g of the first hub 31 and the other end face 32b of the second hub 32 are facing each other and in axial contact (contact).

[0035] In this embodiment, one end face 31g of the first hub 31 and the other end face 32b of the second hub 32 are facing each other in an axially contacting (contacting) state (see Figure 6). However, as shown in Figure 8, with the second hub 32' (small diameter portion 321') of the hub 3' pressed into the rolling bearing 7, one end face 31g' of the first hub 31' of the hub 3' and the other end face 32b' of the second hub 32' may be facing each other in an axially separated state. In this case, a gap 33 will be formed between one end face 31g' of the first hub 31' of the hub 3' and the other end face 32b' of the second hub 32'.

[0036] (Spring 4) The spring 4 is positioned between the pulley 2 and the hub 3. Specifically, the spring 4 is housed in a space U located on the other end side of the rolling bearing 7, which is defined by the inner circumferential surface of the pulley 2, the inner circumferential surface of the outer cylindrical portion 31b of the hub 3, the outer circumferential surface of the cylindrical body 31a of the first hub 31 of the hub 3, and the annular plate portion 31c of the first hub 31. The spring 4 is made of a wire with a square cross-section (for example, oil-tempered wire for springs (compliant with JIS G3560:1994)), and is left-handed (counterclockwise from the other end of the spring 4 towards one end).

[0037] Space U is filled with a lubricant such as grease. The lubricant is added to space U in the form of a paste-like mass when the pulley structure 1 is assembled. The amount added is, for example, about 0.2g. When the pulley structure 1 is operated, the viscosity of the lubricant decreases due to the rise in temperature of space U and shear heating (frictional heat), and the lubricant diffuses throughout space U.

[0038] (A pair of bearings 6 and 7) A pair of bearings 6 and 7 are interposed between the pulley 2 and the hub 3 at one end and the other end, respectively. Specifically, the sliding bearing 6 is interposed in the gap (hereinafter referred to as the "cylindrical gap") between the inner circumferential surface of the other end of the pulley 2 and the outer circumferential surface of the outer cylindrical portion 31b of the first hub 31. A rolling bearing 7 is interposed between the inner circumferential surface 2f of one end of the pulley 2 and the outer circumferential surface of one end of the hub 3. More specifically, the rolling bearing 7 is press-fitted between the inner circumferential surface 2f of one end of the pulley 2 and the first hub outer circumferential surface 31f of the first hub 31, and between the inner circumferential surface 2f of one end of the pulley 2 and the second hub outer circumferential surface 32a of the second hub 32. This pair of bearings 6 and 7 connects the pulley 2 and the hub 3 so that they can rotate relative to each other. The pulley 2 and the hub 3 rotate clockwise (hereinafter referred to as the "positive direction") when viewed from the direction from one end to the other.

[0039] The sliding bearing 6 is an ended annular member, and a gap (not shown) exists between the circumferential ends of the sliding bearing 6. The sliding bearing 6 is made of a hard thermoplastic resin with a Rockwell R scale (according to JIS K7202-2:2001) of 80 to 130. Specifically, the sliding bearing 6 is made of polyacetal resin, polyamide resin, polycarbonate, modified polyphenylene ether, polyester (polybutylene terephthalate, polyethylene terephthalate, etc.), fluororesin, polyphenylene sulfide, polysulfone, amorphous polyarylate, polyetherimide, polyethersulfone, polyetherketones, liquid crystal polymer, polyamideimide, thermoplastic polyimides, syndio-type polystyrene, olefin resins (polyethylene, polypropylene, etc.), styrene resins (ABS resin, polystyrene, etc.), polyvinyl chloride, vinylidene chloride resin, methacrylic resin, polyvinyl alcohol, styrene-based block copolymer resin, etc. However, from the viewpoint of low friction sliding properties and wear resistance, it is more preferable that the sliding bearing 6 be made of polyacetal resin and polyamide resin among these materials. Furthermore, the Rockwell R scale hardness of the sliding bearing 6 is more preferably around 85 to 125.

[0040] Furthermore, the sliding bearing 6 may be a single layer formed from one type of resin composition, or it may be a two or more layer formed from two or more types of resin compositions. However, from the viewpoint of manufacturing cost, it is more preferable for the sliding bearing 6 to be a single layer formed from one type of resin composition. The sliding bearing 6 is manufactured by injection molding using an injection molding machine and a mold (injection molding mold).

[0041] As shown in Figures 5 and 6, the rolling bearing 7 is a contact seal type deep groove ball bearing, comprising an outer ring 71 that abuts against the inner circumferential surface 2f of one end of the pulley 2, an inner ring 72 that abuts against the outer circumferential surface of one end of the hub 3, a plurality of balls 73 (rolling elements) that are separated and held between the outer ring 71 and the inner ring 72 and arranged to roll freely, and annular contact seal members 74 arranged on both axial sides of the plurality of balls 73. By sealing a lubricant such as grease (for example, the same lubricant as the lubricant sealed in the space U) inside the rolling bearing 7, wear of the friction surface of the rolling bearing 7 (the contact surface of the balls 73 with the outer ring 71 and / or inner ring 72) is suppressed.

[0042] (Spring 4) The spring 4 has a region at one end that contacts the pulley 2, a region at the other end that contacts the first hub 31 of the hub 3, and a middle region between the one-end and other-end regions that does not contact either the pulley 2 or the first hub 31 of the hub 3.

[0043] When not subjected to external force, the spring 4 has a constant diameter along its entire length. In this state, the outer diameter of the spring 4 is smaller than the inner diameter of the pulley 2 at the annular surface 2b and larger than the inner diameter of the pulley 2 at the contact surface 2a. The spring 4 is housed in space U with one end region reduced in diameter.

[0044] When no external force is applied to the pulley structure 1 (i.e., when the pulley structure 1 is stopped), the spring 4 is compressed in the axial direction. At this time, the outer circumferential surface of one end of the spring 4 is pressed against the contact surface 2a by the self-elastic restoring force of the spring 4 in the diameter expansion direction, and the other end of the spring 4 is in contact with the outer circumferential surface of the cylindrical body 31a in a slightly expanded diameter state. In other words, the inner circumferential surface of the other end of the spring 4 is pressed against the outer circumferential surface of the cylindrical body 31a by the self-elastic restoring force of the spring 4 in the diameter contraction direction.

[0045] (Alternator 101) As shown in Figure 7, the alternator 101 is located at one end of the pulley structure 1 and comprises a housing 102 and a drive shaft S that is rotatably supported via a rolling bearing 103 located at the other end of the housing 102 and protrudes to the outside at the other end of the housing 102. The rolling bearing 103 is positioned in the axial direction by being sandwiched from both axial sides by the end S1 of the drive shaft S which abuts against one end face 105a of the inner ring 105 and the inward edge 102a of the housing 102 which abuts against the other end face 104a of the outer ring 104. The pulley structure 1 is fixed to the drive shaft S by screwing the male thread formed on the outer circumference of the tip of the drive shaft S into the female thread formed on the inner circumference of the first hub 31. At this time, the hub 3 (and thus the pulley 2) is positioned axially with respect to the alternator 101 (drive shaft S) by abutting one end face 32c of the second hub 32 against the other end face 105b of the inner ring 105 of the rolling bearing 103 of the alternator 101.

[0046] (Operation of pulley structure 1) Next, we will explain the operation of the pulley structure 1.

[0047] First, let's explain the case where the rotational speed of pulley 2 becomes greater than the rotational speed of hub 3 (i.e., when pulley 2 accelerates).

[0048] In this case, pulley 2 rotates relative to hub 3 in the positive direction. As pulley 2 rotates relative to hub 3, one end region of spring 4 moves together with the contact surface 2a and rotates relative to hub 3. This causes spring 4 to twist in the radial expansion direction. The contact force on the contact surface 2a of one end region of spring 4 increases as the twist angle in the radial expansion direction of spring 4 increases. As the twist angle in the radial expansion direction of spring 4 increases and the torsional stress acting on the other end region of spring 4 increases, the other end region of spring 4 slides relative to the outer surface of the cylindrical body 31a in the circumferential direction of pulley 2, against the contact force on the outer surface of the cylindrical body 31a. Then, when the other end region of the spring 4 slides, the other end region of the spring 4 comes into contact with a contact surface (not shown) formed on the hub 3 (first hub 31), and by pressing the hub 3 (first hub 31), torque is transmitted between the pulley 2 and the hub 3.

[0049] Furthermore, when the torsional angle of the spring 4 in the radial expansion direction reaches its limit, the outer circumferential surface of the middle region of the spring 4 comes into contact with the annular surface 2b, thereby restricting further deformation of the spring 4 in the radial expansion direction, and causing the pulley 2 and hub 3 to rotate as a single unit. This prevents damage to the spring 4 due to deformation in the radial expansion direction.

[0050] Next, we will explain the case where the rotational speed of pulley 2 becomes less than the rotational speed of hub 3 (i.e., when pulley 2 slows down).

[0051] In this case, pulley 2 rotates relative to hub 3 in the opposite direction (counterclockwise when viewed from the direction from one end to the other). As pulley 2 rotates relative to hub 3, the region on one end of spring 4 moves together with the contact surface 2a and rotates relative to hub 3. This causes spring 4 to twist in the direction of radial contraction. When spring 4 twists in the direction of radial contraction, the contact force on the contact surface 2a of the region on one end of spring 4 becomes approximately zero, and the region on one end of spring 4 slides relative to the contact surface 2a in the circumferential direction of pulley 2. Therefore, no torque is transmitted between pulley 2 and hub 3.

[0052] Thus, when the hub 3 rotates relative to the pulley 2 in the positive direction, the spring 4 engages with both the pulley 2 and the hub 3, transmitting torque between the pulley 2 and the hub 3. However, when the hub 3 rotates relative to the pulley 2 in the reverse direction, the spring 4 slides against at least one of the pulley 2 and the hub 3 (in this embodiment, the contact surface 2a) (in this embodiment, sliding in the circumferential direction of the pulley 2), and does not transmit torque between the pulley 2 and the hub 3. Furthermore, the pulley structure 1 is configured to transmit or interrupt torque between the pulley 2 and the hub 3 by expanding or contracting the diameter of the spring 4.

[0053] (Method for manufacturing pulley structure 1) Next, we will describe the manufacturing method of the pulley structure 1.

[0054] First, the spring 4 is pressed into the first hub 31 from one end. Next, a sliding bearing 6 is attached to the outer cylinder portion 31b of the first hub 31. Furthermore, the pulley 2 is attached to the first hub 31 from one end. In this state, grease is applied to the outer surface of the first hub 31, which is opposite to the inner surface of the spring 4.

[0055] Next, a rolling bearing 7 is press-fitted between the inner circumferential surface 2f of one end of the pulley 2 and the outer circumferential surface 31f of the first hub 31. Next, the second hub 32 is press-fitted onto the inner circumferential surface 72c of the inner ring 72 of the rolling bearing 7. At this point, the assembly of the pulley structure 1 is temporarily complete, except for the attachment of the end cap 5.

[0056] Next, the manufacturer of the alternator 101 connects the pulley structure 1 to the drive shaft S of the alternator 101 (see Figure 7). Next, the final inspection of the alternator 101 is performed. At this time, the centrifugal force caused by the rotation of the hub 3 spreads the grease to the surfaces forming the space U between the pulley 2 and the first hub 31.

[0057] Finally, attach the end cap 5 to the other end of pulley 2. This completes the pulley structure 1 (see Figure 5).

[0058] (Effects of the above configuration) According to the pulley structure 1 with the above configuration, the rolling bearing 7 is press-fitted between the inner circumferential surface 2f of one end of the pulley 2 and the outer circumferential surface of one end of the hub 3 (the first hub outer circumferential surface 31f and the second hub outer circumferential surface 32a). By sandwiching the rolling bearing 7 from both axial sides between the second contact surface A of the first hub 31 and the third contact surface C of the second hub 32, the rolling bearing 7 can be positioned in the axial direction while being sandwiched from both axial sides between the first contact surface B of the annular plate portion 2e of the pulley 2 and the third contact surface C of the second hub 32. As a result, even if an impact force is applied to the other end side 2d of the pulley 2 while the hub 3 of the pulley structure 1 is connected to the drive shaft S of the alternator 101, this impact force (external force) will act directly on the drive shaft S of the alternator 101, which is fixed to the second hub 32, via the pulley 2, rolling bearing 7, and second hub 32, which are in axial contact with each other. In other words, with the above configuration, even if an impact force is applied to the pulley 2 from the other end to the one end while the pulley structure 1 is connected to the drive shaft S of the alternator 101 located at one end, it is possible to prevent the pulley 2 from shifting position toward the one end relative to the hub 3.

[0059] Furthermore, the first hub 31 has a first hub outer surface 31f that abuts against the inner circumferential surface 72b of the other end of the inner ring 72 of the rolling bearing 7, and the second hub 32 has a second hub outer surface 32a that abuts against the inner circumferential surface 72c of one end of the inner ring 72. This allows the impact force to be distributed to both the first hub 31 and the second hub 32 when an impact force is applied to the pulley 2 from one end to the other. [Examples]

[0060] In the present invention, when the pulley structure is connected to the drive shaft of an auxiliary machine, it is necessary to prevent the pulley from shifting position toward one end relative to the hub even when an impact force is applied to the pulley from one end to the other. Therefore, in this embodiment, pulley structures according to Example 1 and Comparative Examples 1-2 (hereinafter referred to as "each test specimen") were fabricated, and impact tests and disassembly inspections were performed to conduct comparative verification. The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0061] [Manufacturing of pulley structures] A pulley structure (each test specimen) was fabricated in accordance with the method described in the above embodiment, with the exception of attaching the end caps, etc. In this state, in each test specimen, the other end face of the pulley (opening) protrudes by a predetermined amount (approximately 2 mm) beyond the other end face of the hub. Next, the pulley structure (each test specimen) was connected (hinged) to the drive shaft of the alternator to obtain an alternator with a pulley structure. In this state, one end face of the second hub is in contact with the other end face of the inner ring of the alternator's rolling bearing (103). The alternator used was a readily available, generic part (weighing approximately 7 kg) intended for repair purposes.

[0062] [Evaluation of pulley structures: items, methods, criteria] For each test specimen (see Table 2: Example 1 is shown in Figure 5, Comparative Example 1 in Figure 1, and Comparative Example 2 is not shown), impact resistance (presence or absence of pulley misalignment) and manufacturing quality (presence or absence of abnormalities in each part of the actually manufactured product) were verified to determine whether a pulley structure capable of solving the problem of the present invention was obtained.

[0063] [Impact Test] (Test method) The alternator with the pulley structure described above is manually lifted to a height of 10 cm on a surface plate, with the other end face of the pulley facing directly downwards (the alternator facing directly upwards). Then, I released my grip and allowed the alternator with the pulley structure to freefall onto the surface plate. This results in an impact force acting on the pulley (the other end face) from the other end to the one end. The amount of displacement (relative movement) of the pulley relative to the hub at one end was measured and recorded for each test specimen.

[0064] (Judgment criteria) If no displacement of the pulley relative to the hub is observed on one end (considering assembly accuracy, if the displacement is less than 0.2 mm), the impact resistance of the pulley structure is considered to be ensured, and it is given an "a" rating. If a misalignment of one end of the pulley relative to the hub was observed (considering assembly accuracy, if the misalignment amount was 0.2 mm or more), the impact resistance of the pulley structure was deemed insufficient, and a rating of "b" was assigned. From the perspective of suitability for actual use in this application (impact resistance of the pulley structure), pulley structures with a rating of A were deemed to be at an acceptable level.

[0065] [Disassembly inspection] (Test method) In the actual final inspection process of the alternator, if the pulley structure is subjected to the above-mentioned impact due to human error (such as dropping it due to a slip of the hand), it will be excluded from shipment (classified as a defective product) regardless of whether the final inspection was performed. In this evaluation, from the perspective of reliability, pulley structures that received an A rating (passing level) in the above impact test will be disassembled and the presence or absence of abnormalities in each part (rolling bearings, etc.) will be checked visually.

[0066] (Judgment criteria) If no damage or other abnormalities (such as abnormal noise or rotational problems during operation of the rolling bearings) were found in any of the components, the manufacturing quality of the pulley structure was considered to be ensured, and it was given an "a" rating. If any abnormalities such as damage (e.g., abnormal noise or poor rotation during operation of the rolling bearings) were found in any of the components, the manufacturing quality of the pulley structure could not be ensured, and it was given a rating of B. From the perspective of suitability for actual use in this application (ensuring the manufacturing quality of the pulley structure), pulley structures with a rating of A were considered to be at the acceptable level.

[0067] (Overall assessment) The criteria for the overall evaluation (ranking) of the pulley structure as capable of solving this problem were determined as follows, based on the results of the evaluations in the two test items (impact resistance and manufacturing quality) mentioned above. Rank A: If all of the above test items received an "a" rating, it was judged to be completely practical and therefore awarded the highest rank. Rank B: If even one of the above test items received a "b" rating, the solution to this task was deemed insufficient and the candidate received a failing grade.

[0068] (Verification results and discussion) The verification results are shown in Table 2. [Table 2]

[0069] (Example 1, Comparative Examples 1-2) In a pulley structure having a second contact surface A on the first hub, the presence or absence of the first contact surface B or the presence or absence of the third contact surface C was changed and compared. In the case where all contact surfaces A to C are present (Example 1), it was not observed that the pulley shifted to one end relative to the hub due to the impact force applied from the other end to one end of the pulley. The impact resistance was rated as A, no abnormalities were found in any part, and the manufacturing quality was also rated as A (rank A in the overall evaluation).

[0070] In the case where the second contact surface A and the first contact surface B are present but the third contact surface C is not (Comparative Example 1), and in the case where the second contact surface A and the third contact surface C are present but the first contact surface B is not (Comparative Example 2), the impact force from the other end to the one end of the pulley caused the pulley to shift position toward the one end relative to the hub (interfering with the alternator), resulting in an impact resistance rating of B (rank B in the overall evaluation).

[0071] (Effects obtained) Table 2 shows that the pulley structure of Example 1 addresses the problem by having all of the contact surfaces A to C, that is, a configuration in which the pulley, rolling bearing and hub are in axial contact with each other. This makes it easier to prevent the pulley from shifting relative to the hub towards the one end even when an impact force is applied to the pulley from the other end to the one end while it is connected to the drive shaft of an auxiliary machine located at one end. [Explanation of Symbols]

[0072] 1. Pulley structure 2 Pulley Side view of the other end of the 2d pulley 2e Circular plate section 3 Hubs 31. First Hub 32 Second Hub 6. Plain bearings 7 Rolling bearings 71 Outer ring 72 Inner Ring 73 balls 101 Alternator (Auxiliary Equipment) A Second contact surface B 1st contact surface C 3rd contact surface S drive shaft Y-belt

Claims

1. A cylindrical pulley around which the belt is wrapped, A hub provided on the inner circumference side of the pulley and fixed to the drive shaft of an auxiliary device located at one end, A pulley structure comprising an outer ring that abuts against the inner circumferential surface of one end of the pulley, an inner ring that abuts against the outer circumferential surface of one end of the hub, and a rolling bearing press-fitted between the inner circumferential surface of one end of the pulley and the outer circumferential surface of one end of the hub, wherein the pulley is rotatable relative to the hub, The pulley has a first contact surface which is integrally formed on the inner circumferential surface of the pulley and which directly contacts the other end surface of the outer ring of the rolling bearing without the need for a separate member. The hub comprises a first hub having a second contact surface that contacts the other end surface of the inner ring, and a second hub having a third contact surface that contacts one end surface of the inner ring. A pulley structure characterized in that the rolling bearing is clamped between the first contact surface and the third contact surface from both axial sides of the drive shaft, and the axial external force applied to the pulley is transmitted to the drive shaft side via the rolling bearing.

2. The first hub has an outer circumferential surface that abuts against the inner circumferential surface of the other end of the inner ring, The pulley structure according to claim 1, characterized in that the second hub has an outer circumferential surface of the second hub that abuts against the inner circumferential surface of one end of the inner ring.

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