Motor-incorporating roller and power transmission member

The power transmission member includes a connecting member, an intermediate member, and an engagement member. The connecting member has an annular portion. The outer peripheral surface of the annular portion is provided with arc-like portions, and the inner peripheral surface of the annular portion is provided with concave-convex portions. The engagement member includes protrusions and a shaft insertion hole. The arc-like portions of the connecting member are in contact with the inner peripheral surface of the roller body, and the connecting member and the roller body are also secured together by securing means. The intermediate member engages with the concave-convex portions and the protrusions, the shaft insertion hole of the engagement member is maintained at the center of the roller body, and a power unit engages with the shaft insertion hole.

TECHNICAL FIELD

The present invention relates to a motor-incorporating roller having a power transmission member. The present invention also relates to one of the components constituting a motor-incorporating roller and, more particularly, to a power transmission member for transmitting the power of a motor to a roller.

BACKGROUND ART

A motor-incorporating roller is known as a component for a roller conveyor or the like. A motor-incorporating roller includes a motor and a speed reducer in its roller body and rotates the roller body on the outside by driving the motor on the inside. More specifically, the motor-incorporating roller is provided with a power transmission member for transmitting the power of the motor to the roller body and is configured to transmit a rotational force of the motor to the roller body through the power transmission member.

Incidentally, most power transmission members for transmitting the power to the roller body are conventionally configured to be integrally secured onto the inner wall of the roller body in terms of power transmission efficiency, easy productivity, and the like, for example as disclosed in Patent Document 1 (U.S. Pat. No. 7,207,433). A method of press-fitting a power transmission member into a roller body is conventionally known as a method of securing a power transmission member to a roller body.

PRIOR ART DOCUMENT

Patent Document

DISCLOSURE OF INVENTION

Technical Problems

The above-described press-fit power transmission member has a simple structure and is also easy to assemble.

However, the press-fit power transmission member may not be secured to the roller body or power transmission capacity to the roller body may be insufficient due to variations in manufacturing of the roller body, in particular, variation in the inner diameter of the roller body.

That is, if the inner diameter of the roller body is large to some extent, a contact force between the roller body and the power transmission member is insufficient and a friction force is less likely to act between the roller body and the power transmission member so that the power transmission member will idle in the roller body.

In other words, in order to generate an adequate friction force between the roller body and the power transmission member, the inner peripheral surface of the roller body and the outer peripheral surface of the power transmission member need to be accurately machined. The outer diameter of the power transmission member needs to be somewhat slightly larger than the inner diameter of the roller body.

However, even if the outer diameter of the power transmission member is machined to be an appropriate size for the inner diameter of the roller body, the friction force between the roller body and the power transmission member decreases due to secular change and they rotate relative to each other during use of the motor-incorporating roller.

Moreover, while the roller body contains some manufacturing errors and there is variations in the inner diameter of each roller body, a drive shaft of the motor-incorporating roller is disposed in the center of the roller body and the power transmission member has to be disposed in the center of the roller body so that the center of the power transmission member also aligns with the drive shaft. That is, the center of the power transmission member needs to be aligned with the center of each roller body so as to be adapted for roller bodies having variation in the inner diameter thereof.

Accordingly, an object of the present invention, which has been made in view of the foregoing problems in the prior art, is to provide a power transmission member which can be firmly secured to a roller body and the center of which can be aligned with the center of the roller body even if there is variation in manufacturing of the roller body and to provide a motor-incorporating roller including such a power transmission member.

Solution to Problem

A first aspect of the present invention to solve the above problems provides a motor-incorporating roller including a hollow roller body, a power unit including a motor, and a power transmission member, the power unit and the power transmission member being contained within the roller body, and a rotational force of the power unit being transmitted to the roller body through the power transmission member,

wherein the power transmission member includes a connecting member that includes an annular portion, part or all of the outer peripheral surface thereof is provided with an arc-like portion, and the inner peripheral surface thereof is provided with a concave-convex portion, an intermediate member having elasticity, and an engagement member including an outer engagement portion and an inner engagement portion,

wherein the connecting member, the intermediate member, and the engagement member are separate from the roller body,

wherein the arc-like portion on the outer peripheral surface of the connecting member is in contact with the inner peripheral surface of the roller body, and the connecting member is secured within the roller body by securing means, the securing means being at least one of bonding, welding, fastening element, and mechanical engagement obtained by recessing the roller body,

wherein the intermediate member engages with the concave-convex portion of the connecting member and the outer engagement portion of the engagement member to maintain the inner engagement portion of the engagement member at the center of the roller body, and

wherein the power unit engages with the inner engagement portion of the engagement member.

According to the present aspect, the power of the power unit can be reliably transmitted from the connecting member of the power transmission member to the hollow roller body through the securing means, which is at least one of bonding, welding, fastening element, and mechanical engagement obtained by recessing the roller body, regardless of friction. The fastening element includes a rivet, pin, screw, etc.

In the present aspect, since the inner peripheral surface side of the annular portion of the connecting member is provided with the concave-convex portion, the engagement member has the outer engagement portion, and the intermediate member engages with the concave-convex portion of the connecting member and the outer engagement portion of the engagement member, the connecting member, the intermediate member, and the engagement member of the power transmission member cannot rotate relative to one another.

Also, since the power unit engages with the inner engagement portion of the engagement member, the power unit transmits power to the power transmission member. Therefore, when the power unit transmits power to the engagement member, the connecting member, the intermediate member, and the engagement member rotate integrally.

The arc-like portion on the outer peripheral surface of the connecting member is in contact with the inner peripheral surface of the roller body and the connecting member is integrally secured within the roller body by the mechanical engagement obtained by recessing the roller body and/or the fastening element so that the power is reliably transmitted to the roller body through the power transmission member upon operation of the power unit and, thus, the roller body rotates. That is, since the connecting member and the roller body are secured integrally at least so as not to rotate relatively to each other, the power is reliably transmitted between the two.

The intermediate member is elastic and engages with the concave-convex portion of the connecting member and the outer engagement portion of the engagement member, and the inner engagement portion of the engagement member is maintained at the center of the roller body, thereby engaging the inner engagement portion of the engagement member with the power unit. That is, if the center of the roller body and the center of the power transmission member are not coincident, the intermediate member elastically deforms and compensates for misalignment so that the inner engagement portion of the engagement member can be engaged with the power unit with the center of the power transmission member and the center of the roller body being aligned with each other.

The connecting member is preferably deformable. In particular, it is desirable for the connecting member to be radially contractible.

According to this preferable aspect, deformability of the connecting member allows the connecting member to easily conform to the inner peripheral surface of the hollow roller body. That is, when the inner diameter of the roller body is smaller than the connecting member, the connecting member is allowed to deform and to enter the roller body.

Preferably, the annular portion of the connecting member includes a plurality of the arc-like portions each of which is arranged at a plurality of positions on the same circumference, and a plurality of recesses each of which is recessed radially inwardly from the annular portion, wherein the arc-like portions adjacent to each other are connected by the recess.

According to this preferable aspect, when the connecting member is pressed against the inner surface of the hollow roller body, the recesses undergo deformation and the arc-like portions come closer to each other so that the connecting member can be easily reduced in diameter and disposed within the roller body.

The fastening element is preferably a rivet.

According to this preferable aspect, the connecting member can be easily connected to the roller body. The connecting member can also be inexpensively connected to the roller body.

The connecting member preferably includes an inner protrusion that is contiguous with at least the arc-like portion of the annular portion and extends radially inwardly.

According to this preferable aspect, the arc-like portion of the connecting member is reinforced. That is, the arc-like portion would be less likely to deform if an external force is applied radially inwardly to the arc-like portion. The roller body and the connecting member are easily secured by the securing means, accordingly.

An annularly continuous inner protrusion constituting an inward flange improves the rigidity of the entire connecting member.

Preferably, the annular portion of the connecting member includes a plurality of arc-like portions that are provided with an inner wall contiguous with the arc-like portion at an axial end thereof and that extend radially inwardly, and a plurality of recesses which are provided with no inner wall, or an inner wall smaller than that of the arc-like portion, wherein the arc-like portions and the recesses are annularly connected.

According to this aspect, an elasticity of the recess can be made different from an elasticity of the arc-like portion. In other words, the elasticity of the recess can be made smaller than that of the arc-like portion. Consequently, when the annular portion is reduced in diameter by compression, the arc-like portion maintains an arc-like shape and the recess undergoes deformation. As such, the arc-like shape makes tight contact with the roller body when the connecting member is inserted into the roller body.

Preferably, the annular portion of the connecting member includes a plurality of arc-like portions and a plurality of recesses more easily elastically deformable compared to the arc-like portion, wherein the arc-like portions and the recesses are annularly connected.

According to this aspect, the arc-like shape makes tight contact with the roller body when the connecting member is inserted into the roller body.

Preferably, the annular portion of the connecting member includes a plurality of arc-like portions and a plurality of recesses, the arc-like portions and the recesses are annularly connected, and the recess is arc-like in shape.

According to this aspect, when the connecting member is inserted into the roller body, each part of the recess deforms uniformly and the arc-like shape is likely to be maintained.

The connecting member is desirably disposed within the roller body with the annular portion being radially compressed.

Preferably, the outer peripheral surface of the intermediate member is provided with a plurality of protrusions protruding radially outwardly and a plurality of retraction portions retracting radially inwardly, and the protrusions adjacent to each other are connected by the retraction portion, wherein the protrusion and the retraction portion of the intermediate member engage with the corresponding concave-convex portion of the connecting member.

According to this preferable aspect, a rotational force can be reliably transmitted between the intermediate member and the connecting member regardless of friction.

A second aspect of the present invention provides a power transmission member that is contained within a hollow roller body of a motor-incorporating roller and transmits a rotational force from an output shaft of a power unit including a motor disposed within the roller body to the roller body,

the power transmission member including a connecting member that includes an annular portion, part or all of the outer peripheral surface thereof is provided with an arc-like portion, and the inner peripheral surface thereof is provided with a concave-convex portion, an intermediate member having elasticity, and an engagement member including an outer engagement portion and an inner engagement portion,

wherein the connecting member, the intermediate member, and the engagement member are separate from the roller body,

wherein the arc-like portion on the outer peripheral surface of the connecting member is in contact with the inner peripheral surface of the roller body, and the connecting member is secured within the roller body by securing means, the securing means being at least one of bonding, welding, fastening element, and mechanical engagement obtained by recessing the roller body,

wherein the intermediate member engages with the concave-convex portion of the connecting member and the outer engagement portion of the engagement member to maintain the inner engagement portion of the engagement member at the center of the roller body, and

wherein the power unit engages with the inner engagement portion of the engagement member.

According to the second aspect of the present invention, the connecting member of the power transmission member is firmly and integrally secured within the roller body by the securing means, which includes at least one of bonding, welding, fastening element, and mechanical engagement obtained by recessing the roller body. Furthermore, the elastic deformation of the intermediate member allows the power transmission member to be aligned with the center of the roller body and, thus, the power of the power unit can be reliably transmitted from the connecting member of the power transmission member to the hollow roller body.

The connecting member of the power transmission member is preferably deformable.

Preferably, the annular portion of the connecting member of the power transmission member includes a plurality of the arc-like portions arranged at a plurality of positions on the same circumference and a plurality of recesses each of which is recessed radially inwardly from the annular portion, wherein the arc-like portions adjacent to each other are connected by the recess.

The fastening element of the power transmission member is desirably a rivet.

The connecting member of the power transmission member desirably includes an inner protrusion that is contiguous with at least the arc-like portion of the annular portion and extends radially inwardly.

Preferably, the annular portion of the connecting member of the power transmission member includes a plurality of arc-like portions that are provided with an inner wall contiguous with the arc-like portion at an axial end thereof and that extend radially inwardly and a plurality of recesses which are provided with no inner wall, or an inner wall smaller than that of the arc-like portion, wherein the arc-like portions and the recesses are annularly connected.

Preferably, the annular portion of the connecting member of the power transmission member includes a plurality of arc-like portions and a plurality of recesses, the arc-like portions and the recesses are annularly connected, and each of the recesses is easily elastically deformable compared to the arc-like portion.

Preferably, the annular portion of the connecting member of the power transmission member includes a plurality of arc-like portions and a plurality of recesses, the arc-like portions and the recesses are annularly connected, and each of the recesses is arc-like in shape.

Preferably, the outer peripheral surface side of the intermediate member of the power transmission is provided with a plurality of protrusions protruding radially outwardly and a plurality of retraction portions retracting radially inwardly, the protrusions adjacent to each other are connected by the retraction portion, and the protrusions and the retraction portions of the intermediate member engage with the corresponding concave-convex portions of the connecting member.

Effect of Invention

The use of the motor-incorporating roller of the present invention allows the power of the power unit to be reliably transmitted from the connecting member of the power transmission member to the hollow roller body regardless of friction.

Additionally, the use of the power transmission member of the present invention allows the power of the power unit to be reliably transmitted to the hollow roller body regardless of friction.

DESCRIPTION OF EMBODIMENT

A motor-incorporating roller according to an embodiment of the present invention will now be described.

A motor-incorporating roller1of the present embodiment is characterized by a power transmission member2for transmitting a driving force of a motor12to a roller body11, and the rest of the basic structure are similar to that known in the art. First, the basic structure of the motor-incorporating roller1is simply described.

As illustrated inFIGS. 1 to 3, the basic structure of the motor-incorporating roller1includes a hollow cylindrical roller body11and cover members41,42and is configured to have a power unit22including a motor12and a speed reducer13therein. In the embodiment, the motor12, the speed reducer13, and a circuit board43are integrated into a motor unit3, which is contained within the roller body11. Part of the motor unit3constitutes the power unit22in the embodiment.

The roller body11is a cylinder with both ends open. The cover members41and42are attached so as to cover both ends of the roller body11.

As illustrated inFIG. 2, the cover member41(on the left side inFIG. 2) includes a combined roller body fitting member52, bearing54, and body-side shaft member53. The other cover member42(on the right side inFIG. 2) includes a combined roller body fitting member55and bearing56. The body-side shaft member53has a cross-section, part or all of which is not circular. The cross-section is approximately hexagonal in the embodiment.

As illustrated inFIGS. 2 to 4, the motor unit3includes a cylindrical case44, and the motor12, the speed reducer13, and the circuit board43are contained within the case44. The case44has therein a fixed-side shaft45extending outwardly from one axial end and a drive-side shaft46(power unit) extending outwardly from the other axial end.

The fixed-side shaft45is a shaft that is inserted into the bearing56of the other cover member42with the motor unit3disposed within the roller body11, serving as a body-side shaft member of the roller body11.

The drive-side shaft46is a shaft that is connected to a power transmission member2, described below, with the motor unit3disposed within the roller body11, serving as a rotational shaft that outputs the power of the power unit22to the roller body11.

Note that both the fixed-side shaft45and the drive-side shaft46have an approximately hexagonal cross-section.

A power transmission member2as a feature of the invention will now be described.

The power transmission member2of the embodiment is a member that is disposed within the roller body11of the motor-incorporating roller1and transmits the power of the motor12to the roller body11. In order to perform its function, the power transmission member2includes a concave-convex member4(connecting member), an intermediate member5, and an engagement member6as illustrated inFIG. 5andFIGS. 6A-6B.

The concave-convex member4is made of a rigid metal such as steel, zinc, or aluminum. The concave-convex member4is an annular or cylindrical hollow member. The concave-convex member4has a portion protruding radially outwardly and a portion recessed radially inwardly.

Specifically, the concave-convex member4includes a plurality of arc-like protrusions7, recesses8recessed radially inwardly, and inner protrusions9. In the embodiment, the concave-convex member4includes four arc-like protrusions7, four recesses8, and four inner protrusions9.

The outer periphery of the arc-like protrusion7has an outwardly convex arc-like surface. The outer periphery of the recess8has an inwardly convex arc-like surface.

The arc-like protrusion7(arc-like portion) is a portion that protrudes radially outwardly on the annular concave-convex member4. The outer periphery of the arc-like protrusion7has a curved surface that is convex radially outwardly. The arc-like protrusions7are provided at four positions on the circumference of the concave-convex member4. While the arc-like protrusions7are preferably disposed on the same circumference, there may be some manufacturing errors in many cases.

The inner periphery of the arc-like protrusion7provides a concave curved surface16. The thickness, i.e., a distance between the outer and inner peripheral surfaces, of the arc-like protrusion7is thin so that a rivet35, described below, can penetrate it.

The recesses8are contiguous with the arc-like protrusion7on both circumferential sides of the concave-convex member4. The recess8is a portion that is recessed on the outer peripheral side of the annular concave-convex member4, and the recesses8are provided at four positions on the circumference of the concave-convex member4.

The outer periphery of the recess8has a concave curved surface. That is, the recess8is recessed radially inwardly relative to the arc-like protrusion7.

The inner peripheral surface of the recess8protrudes radially inwardly and provides a convex surface18on the inner peripheral side of the concave-convex member4.

The arc-like protrusions7and the recesses8are alternately arranged in the circumferential direction to be annularly continuous, thereby forming an annular portion15. That is, the concave-convex member4has a structure in which it protrudes radially outwardly at the arc-like protrusions7and it is recessed radially inwardly at the recesses8. On the other hand, the concave surface16being the inner peripheral surface of the arc-like protrusion7is contiguous with the convex surface18being the inner peripheral surface of the recess8inside the concave-convex member4, which forms a concave-convex portion19.

The inner protrusion9is a plate-shaped portion that is contiguous with the arc-like protrusion7. In the embodiment, the inner protrusion9is contiguous with the arc-like protrusion7and extends radially inwardly to form an inner wall. The inner wall, located at the axial end of the arc-like protrusion7, is contiguous with the arc-like protrusion7and extends radially inwardly.

A surface constituting the inner protrusion9intersects a surface constituting the arc-like protrusion7and extends radially inwardly of the concave-convex member4from an end of the arc-like protrusion7. The inner protrusions9are disposed on the same end side of the arc-like protrusions7. That is, each inner protrusion9is configured such that a plurality of sections (four sections) of an inward annular flange are radially cut away. In other words, the inner protrusions9have a structure such that the inward annular flange is provided with a plurality of slits extending radially.

The inner protrusion9functions as a rib reinforcing the arc-like protrusion7. That is, the arc-like protrusion7would be less likely to deform if an external force is applied radially inwardly to the arc-like protrusion7. On the other hand, since the recess8has no member corresponding to the inner protrusion9, the recess8is subject to elastic deformation compared to the arc-like protrusion7.

The concave-convex member4has an annular configuration formed of a thin plate member as described above and the inside of the annular portion15is provided with an intermediate member receiving region R1. The above-described concave-convex portion19is a part of the intermediate member receiving region R1.

The intermediate member5is then described.

The intermediate member5is made of an elastic material such as rubber and is a short cylindrical body having an annular configuration as illustrated inFIGS. 6A and 6B. The outer shape of the intermediate member5is substantially similar to a contour of the intermediate member receiving region R1of the concave-convex member4and is sized slightly smaller than the intermediate member receiving region R1. The width of the intermediate member5is sized such that it can be disposed within the intermediate member receiving region R1of the concave-convex member4.

The intermediate member5includes protrusions25and retraction portions26. That is, the intermediate member5includes protrusions25protruding radially outwardly at a plurality of positions (four positions) on the circumference and retraction portions26retracting radially inwardly at a plurality of positions (four positions) on the circumference.

The protrusion25is a portion that protrudes radially outwardly on the outer peripheral surface of the intermediate member5having an annular configuration. As illustrated inFIGS. 6A-6B, the protrusion25has a groove27. The groove27extends in the width direction of the intermediate member5.

The inner peripheral side of the protrusion25of the intermediate member5is provided with a concave portion28.

The retraction portion26is a portion that is recessed radially inwardly of the outer peripheral surface of the annular intermediate member5. The outer surface of the retraction portion26is concave. The retraction portion26connects protrusions25adjacent to the retraction portion26.

The inner peripheral side of the retraction portion26of the intermediate member5is provided with a convex portion29protruding radially inwardly.

The inside of the annular intermediate member5is provided with an engagement member receiving region R2defined by the concave portions28and the convex portions29. The engagement member receiving region R2provides an inner engagement portion of the intermediate member5. The engagement member receiving region R2can be expanded by applying an external force.

The protrusions25and the retraction portions26of the intermediate member5constitute an outer engagement portion. The outer shape of the intermediate member5is substantially similar to a space that the intermediate member receiving region R1of the concave-convex member4occupies. The intermediate member5is sized slightly smaller than the intermediate member receiving region R1.

The engagement member6is then described.

The engagement member6is made of a rigid metal such as steel, zinc, or aluminum. The width of the engagement member6is sized such that it can be disposed within the engagement member receiving region R2of the intermediate member5. The engagement member6includes a cylindrical main body30and four protrusions31(outer engagement portions).

The cylindrical main body30is a cylindrical portion, the inside of which is provided with a shaft insertion hole32(inner engagement portion). The shaft insertion hole32is a polygonal hole (e.g., a hexagonal hole).

The protrusion31is a substantially rectangular prismatic portion, which is integrally secured to the outer peripheral surface of the cylindrical main body30and extends radially outwardly. In the embodiment, the four protrusions31are secured to the outer peripheral surface of the cylindrical main body30at equal angular intervals.

The appearance of the engagement member6is substantially similar to the engagement member receiving region R2of the intermediate member5. The engagement member6is sized slightly larger than a space that the engagement member receiving region R2occupies.

The power transmission member2is constructed by combining the concave-convex member4, the intermediate member5, and the engagement member6. That is, the intermediate member5is inserted into the intermediate member receiving region R1of the concave-convex member4, and the engagement member6is press-fit into the engagement member receiving region R2of the intermediate member5.

The intermediate member5is elastically deformable and is inserted into the intermediate member receiving region R1of the concave-convex member4while being elastically deformed.

While the engagement member6is rigid, the inner wall surface of the intermediate member5forming the engagement member receiving region R2is elastically deformable. The engagement member6is press-fit into the engagement member receiving region R2by expanding the inner wall of the intermediate member5.

Since the intermediate member5is sized slightly smaller than the intermediate member receiving region R1in the foregoing example, the intermediate member5can be smoothly inserted into the intermediate member receiving region R1of the concave-convex member4.

Alternatively, the intermediate member5may be press-fit into the intermediate member receiving region R1of the concave-convex member4with the intermediate member5sized slightly larger than the intermediate member receiving region R1.

All of the concave-convex member4, the intermediate member5, and the engagement member6of the power transmission member2are annular in shape and the engagement member6is mounted in the concave-convex member4through the intermediate member5. Consequently, the center of the shaft insertion hole32of the engagement member6can be moved slightly eccentrically by elastic formation of the intermediate member5.

That is, if the center of the shaft insertion hole32of the engagement member6and the center of the roller body11(i.e., the center of rotation of the drive-side shaft46) are not coincident with no external force applied to the intermediate member5, the elastic deformation of the intermediate member5subjected to an external force moves the position of the engagement member6so that the center of the shaft insertion hole32of the engagement member6and the center of rotation of the drive-side shaft46can be aligned with each other. The drive-side shaft46disposed in the center of the roller body11is inserted into the shaft insertion hole32of the engagement member6.

Procedures for securing the power transmission member2to the roller body11will now be described.

As illustrated inFIGS. 7A and 15A, the concave-convex member4, the intermediate member5, and the engagement member6constituting the power transmission member2are present separately, i.e., are not combined with each other.

First, only the concave-convex member4is placed at a desired position in the roller body11. The desired position in the roller body11is a position at which the drive-side shaft46(power unit) shown inFIG. 1is placed. The drive-side shaft46is not shown for convenience inFIGS. 11A-11C.

Here, assuming the outer diameter of the concave-convex member4is slightly larger than the inner diameter of the roller body11, the concave-convex member4is allowed to deform and to enter the roller body11. That is, the concave-convex member4includes the arc-like protrusions7and the recesses8, and when the arc-like protrusions7are pressed against an inner peripheral surface11aof the roller body11, the recesses8undergo deformation and the arc-like protrusions7get close to each other, which reduces the diameter of the concave-convex member4. In other words, the arc-like protrusions7move radially inwardly.

That is, while the material making up the concave-convex member4is a rigid material such as metal, the provision of the arc-like protrusions7and the recesses8allows the concave-convex member4to deform slightly.

However, since the recess8is easily deformable compared to the arc-like protrusion7as described above, the concave-convex member4reduces its diameter while maintaining the arc-like shape of the arc-like protrusion7and is mounted in the inner peripheral surface11aof the roller body11.

The arc-like protrusion7maintains a shape conforming to the inner peripheral surface11aof the roller body11in the embodiment so that the arc-like protrusion7is in close contact with the inner peripheral surface11aof the roller body11. The concave-convex member4will be disposed within the roller body under radial compression accordingly.

As illustrated inFIGS. 7B and 15B, when the concave-convex member4is placed at the desired position in the roller body11, the concave-convex member4is secured to the roller body11by the rivet35(fastening element) shown inFIG. 17A.

The rivet35is described hereinafter.

As illustrated inFIG. 17A, the rivet35has an umbrella head35aand a cylindrical shank35b. The inside of the shank35bis provided with a space37. An opening communicating with the space37is formed at the end portion of the shank35b. That is, the end of the shank35bis provided with an annular opening edge40.

The rivet35can be a self-piercing rivet available from FUKUI BYORA CO., LTD., which is made of a material such as high carbon steel, stainless steel, or aluminum.

The rivet35can fasten two members together using a jig36a. The jig36ahas a support surface34. The support surface34is a plane or a curved surface conforming to the concave surface16on the inner peripheral side of the arc-like protrusion7of the concave-convex member4. The support surface34is provided with a blind hole48. The center of the blind hole48is provided with a protrusion49. The protrusion49has a particular shape such as a cone and is tapered. That is, the cross-sectional diameter of a connecting portion at which the protrusion49intersects the blind hole48is larger than the inner diameter of the shank35b.

As illustrated inFIG. 18A, the space37is aligned with the end of the protrusion49with the opening edge40of the space37of the shank35bof the rivet35opposed to the end side of the protrusion49of the jig36a. When the head35aof the rivet35is then struck with a hammer or the like (not shown), the shank35bof the rivet35penetrates the roller body11and recesses the concave-convex member4as illustrated inFIG. 18B. The opening edge40of the shank35bis further pressed against a base end of the protrusion49larger than the inner diameter of the shank35bthrough the concave-convex member4. As a result, the shank35bof the rivet35is broken from its end side to be expanded as illustrated inFIGS. 18C-18D.

The rivet35, which penetrates the roller body11and the concave-convex member4, can fasten them together using a jig36bshown inFIG. 17B. The jig36bhas a structure in which the central portion of a blind hole38formed on a flat plate is provided with a substantially conical protrusion39.

As illustrated inFIG. 19A, the jig36bis disposed on the inner peripheral side of the concave-convex member4and the rivet35is disposed outside the roller body11. The center of the shank35bof the rivet35and the protrusion39of the jig36bare aligned with each other. When the head35aof the rivet35is struck with a hammer or the like (not shown), the rivet35penetrates the roller body11and the concave-convex member4as illustrated inFIG. 19B.

Further, as illustrated inFIGS. 19C-19D, the shank35bof the rivet35is abutted against the blind hole38and the protrusion39of the jig36b. Consequently, the shank35bof the rivet35is broken from its end side to be expanded on the blind hole38so that the broken shank35bengages with the concave surface16(i.e., the inner peripheral surface) of the concave-convex member4. The head35aof the rivet35engages with the outer peripheral surface of the roller body11. Thus, the roller body11and the concave-convex member4are held between the head35aand the broken shank35bof the rivet35.

Referring back toFIG. 7B, the roller body11and the arc-like protrusion7of the concave-convex member4are fastened by the rivet35. That is, the jig36ais disposed within the intermediate member receiving region R1, is abutted on the concave surface16of the concave-convex member4, and is opposed to the rivet35outside the roller body11. When the head35aof the rivet35is struck with a hammer or the like (not shown), the end of the shank35bof the rivet35penetrates the roller body11and bites into the concave-convex member4(arc-like protrusion7). Thereafter, the end of the shank35bis broken inside the concave-convex member4(arc-like protrusion7) to be expanded, and the roller body11and the concave-convex member4are secured together as illustrated inFIGS. 7C and 15C.

Alternatively, the roller body11and the arc-like protrusion7of the concave-convex member4are fastened by the rivet35as illustrated inFIG. 11B. That is, the jig36bis disposed within the intermediate member receiving region R1, is abutted on the concave surface16of the concave-convex member4, and is opposed to the rivet35outside the roller body11. When the head35aof the rivet35is struck with a hammer or the like (not shown), the shank35bof the rivet35penetrates the roller body11and the concave-convex member4(arc-like protrusion7) and the end of the shank35bis abutted against the jig36bto be broken. Consequently, the end of the shank35bis expanded laterally on the blind hole38of the jig36b, the head35aof the rivet35makes close contact with the roller body11, and broken portions of the shank35bmakes close contact with the inner peripheral surface of the arc-like protrusion7of the concave-convex member4. That is, the roller body11and the concave-convex member4are secured together as illustrated inFIG. 11C.

Next, the intermediate member5is mounted in the concave-convex member4secured to the roller body11, continued fromFIGS. 7A-7CorFIGS. 11A-11C.

The outer diameter of the intermediate member5is smaller than the inner diameter of the roller body11as illustrated inFIG. 8A or 12A. As such, the intermediate member5can smoothly move in the roller body11and reach the position of the concave-convex member4.

The intermediate member5is inserted into the intermediate member receiving region R1of the concave-convex member4as illustrated inFIG. 8B or 12B. The intermediate member5is disposed within the intermediate member receiving region R1while being elastically deformed. At that time, the protrusions25and the retraction portions26of the intermediate member5shown inFIGS. 6A-6Bmake close contact with the corresponding concave surfaces16and convex surfaces18of the concave-convex member4, respectively. Consequently, the concave-convex member4and the intermediate member5are fit in a concave-convex manner and cannot rotate relative to each other.

The protrusion25of the intermediate member5has the groove27and the protrusion25elastically deforms so that the width of the groove27narrows. As illustrated inFIG. 10B, alignment of the groove27with the position of the rivet35prevents the intermediate member5from interfering with the rivet35or the concave-convex member4recessed by the rivet35and facilitates placement of the intermediate member5within the concave-convex member4.

The intermediate member5, which has entered the intermediate member receiving region R1, abuts against the inner protrusion9of the concave-convex member4to stop and is securely disposed within the intermediate member receiving region R1as illustrated inFIG. 8C or 12C.

Finally, the engagement member6is mounted in the engagement member receiving region R2of the intermediate member5, continued fromFIGS. 8A-8CorFIGS. 12A-12C.

Since the outer diameter of the engagement member6is smaller than the inner diameter of the roller body11as illustrated inFIGS. 9A, 13A, and 16A, the engagement member6can easily move in the roller body11and quickly reach the position of the intermediate member5.

The engagement member6is then press-fit into the engagement member receiving region R2of the intermediate member5as illustrated inFIGS. 9B and 13B. At that time, the intermediate member5undergoes elastic deformation and the engagement member6is disposed within the engagement member receiving region R2as illustrated inFIGS. 9C, 13C, and16B.

The protrusions31of the engagement member6engage with the corresponding concave portions28of the intermediate member5. As such, the engagement member6and the intermediate member5cannot rotate relative to each other.

The concave-convex member4has the elastically deformable intermediate member5so that the position of the engagement member6can be fine-tuned. In other words, the elastic deformation of the intermediate member5allows the position of the engagement member6to be moved.

Specifically, even if the center of the power transmission member2secured to the roller body11does not coincide with the center of the roller body11under natural conditions, the drive-side shaft46(output shaft) can be inserted into the shaft insertion hole32of the engagement member6as illustrated inFIGS. 10A and 14by elastically deforming the intermediate member5.

When the drive-side shaft46, having a hexagonal cross-section, is inserted into the shaft insertion hole32or a hexagonal hole, they are integrated so as not to rotate relative to each other.

A structure for securing the power transmission member2and the roller body11together is as follows.

The intermediate member5is fit in the concave-convex member4(the intermediate member receiving region R1), and the intermediate member5and the concave-convex member4cannot rotate relative to each other.

Further, the engagement member6is fit in the intermediate member5(the engagement member receiving region R2), and the engagement member6and the intermediate member5cannot rotate relative to each other.

Furthermore, the roller body11and the four arc-like protrusions7of the concave-convex member4are securely fastened by the rivets35so that the roller body11and the power transmission member2are firmly secured to each other and cannot rotate relative to each other. Note that if the roller body11and at least one arc-like protrusion7are securely fastened by the rivet35, the roller body11and the concave-convex member4cannot rotate relative to each other.

Since the engagement member6and the roller body11cannot rotate relative to each other, a rotational force of the power unit22is reliably transmitted to the roller body11through the engagement member6, the intermediate member5, and the concave-convex member4. When the drive-side shaft46of the power unit22rotates, the roller body11rotates together therewith.

While the power transmission member2and the roller body11are securely fastened by the rivets35in the above-described example, the roller body11and the concave-convex member4of the power transmission member2can be secured together using mechanical engagement. That is, caulking portions60, caulked by strongly striking specific parts of the roller body11, are provided as illustrated inFIGS. 20A-20B. The provision of the caulking portions60causes the arc-like protrusions7of the concave-convex member4of the power transmission member2to be partially recessed. Thus, the roller body11and the concave-convex member4can be integrated so as not to rotate relatively to each other.

The power transmission member2is integrally secured to the roller body11as described above. Therefore, the power transmission member2can be firmly secured to the roller body11compared to a securing method relying on friction.

Furthermore, even if there is variation in the inner diameter of the roller body11due to a manufacturing error, the roller body11and the power transmission member2is firmly secured together by the rivets35(fastening element) or caulking (mechanical engagement). In this case, if the center of the roller body11and the center of the power transmission member2(i.e., the center of the shaft insertion hole32of the engagement member6) are not coincident, the elastic deformation of the intermediate member5allows the center of the shaft insertion hole32of the engagement member6to be aligned with the center of the roller body11.

The power transmission members2and62(i.e., concave-convex member4and connecting member64) may be secured to the roller body11by adhesive bonding or welding instead of using the rivet35(fastening element) or the crimp (mechanical engagement) as described above. That is, the inner peripheral surface11aof the roller body11and the concave-convex member4(connecting member) of the power transmission members2or the connecting member64of the power transmission member62may be secured together by adhesive bonding or spot welding, as depicted schematically at135aand135binFIGS. 22A and 22B, respectively.

Moreover, the roller body11and the power transmission members2,62(i.e., concave-convex member4and connecting member64) may be secured together by a combination of at least two of bonding, welding, fastening element, and mechanical engagement with the power transmission members2,62obtained by recessing the roller body11.

A connecting member64of a power transmission member62shown inFIG. 21can be used instead of the concave-convex member4(connecting member) of the power transmission member2shown inFIGS. 6A and 6B. The power transmission member62includes a connecting member64, an intermediate member5, and an engagement member6. The intermediate member5and the engagement member6of the power transmission member62are the same as the intermediate member5and the engagement member6of the power transmission member2, respectively.

The connecting member64has a structure substantially identical to the concave-convex member4, where the same elements are denoted by the same reference numerals and redundant descriptions are omitted.

The connecting member64has a flange69that is configured such that the inner protrusions9adjacent to one another are arranged continuously instead of the inner protrusions9of the concave-convex member4. The flange69is an inward flange having a hole69aand is formed around the entire circumference of the annular portion15of the connecting member64. That is, the outer peripheral portion of the flange69is contiguous with the annular portion15around the entire circumference. Since the flange69increases the rigidity of the connecting member64, the connecting member64would be less likely to deform if an external force is applied radially.

Also, since the outer peripheral portion of the flange69is contiguous with the annular portion15around the entire circumference, the flange69would be less likely to deform if a force in the normal direction is applied to the flange69. That is, even if the intermediate member5is pressed and a load in the normal direction is applied to the flange69when the intermediate member5is disposed within the intermediate member receiving region R1, the flange69is less likely to deform. Thus, the intermediate member5is securely disposed within the intermediate member receiving region R1.