JP2006022857A - Sprocket retention section structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sprocket retention section structure for reducing the weight of a sprocket retention section. <P>SOLUTION: In the driven flange structure of the chain type power transmission mechanism of a vehicle, a driven flange 70 has a sprocket mounting section 72 and a wheel mounting section 73, and the sprocket mounting section 72 and the wheel mounting section 73 are connected by a connection wall section 74 as a thin structure hollowing out the inside of a column. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sprocket holding portion structure of a chain type power transmission mechanism suitable for a vehicle such as a motorcycle.

2. Description of the Related Art Conventionally, in a chain type power transmission mechanism of a vehicle, there is one in which a sprocket holding portion (driven flange) is reduced in weight in order to reduce the weight of the vehicle (see, for example, Patent Document 1).
JP-A-11-82687

However, the conventional technology has a problem that the cost of parts when replacing the sprocket is relatively high because the sprocket holding portion and the sprocket (driven sprocket) are integrally formed. For this reason, it is desirable to reduce the weight of the sprocket holding part with a relatively high degree of design freedom, while using a configuration in which the sprocket holding part and the sprocket are releasably coupled using an existing fastener.
Accordingly, the present invention provides a sprocket holding portion structure that can reduce the weight of the sprocket holding portion.

  As a means for solving the above problems, the invention described in claim 1 is directed to a sprocket holding portion structure of a chain type power transmission mechanism (for example, the chain type power transmission mechanism 50 of the embodiment) of a vehicle (for example, the motorcycle 1 of the embodiment). The sprocket holding portion (for example, the driven flange 70 of the embodiment) has a sprocket attachment portion (for example, the sprocket attachment portion 72 of the embodiment) and a wheel attachment portion (for example, the wheel attachment portion 73 of the embodiment). The portion and the wheel mounting portion are connected by a thin-walled structure (for example, the connecting wall portion 74 of the embodiment) that penetrates the inside of the cylinder.

  According to this configuration, it is possible to reduce the weight of the sprocket holding portion by connecting the sprocket attachment portion and the wheel attachment portion with a thin structure.

According to a second aspect of the present invention, the wheel mounting portion is configured such that the wheel mounting portion (for example, the damper rubber 71 of the embodiment) is disposed on the disk-shaped portion (for example, the base portion 83 of the embodiment) via the buffer member (for example, the damper rubber 71 of the embodiment). It has a plurality of protrusions (for example, damper bosses 84 of the embodiment) that engage with the rear wheel 55).
According to this configuration, the disk-shaped part becomes a thin-walled structure, and the weight of the sprocket holding part can be further reduced.

The invention described in claim 3 is characterized in that a thinning portion (for example, each thinning portion 92a, 92b, 92c in the embodiment) is provided in each projection portion.
According to this configuration, the plurality of protrusions become a hollow (thin wall) structure, and the sprocket holding portion can be further reduced in weight.

  Here, in the sprocket holding portion structure, in order to be able to efficiently transmit torque while suppressing the amount of deflection while maintaining the buffer performance of each buffer member, the invention according to claim 4 is characterized in that each of the protrusions includes: Six are arranged on the disk-like portion so as to be equally spaced in the circumferential direction.

The invention described in claim 5 is characterized in that the disk-like portion is provided so as to be inclined away from the wheel as it goes from the inner circumference side toward the outer circumference side.
According to this configuration, the distance between the disc-shaped portion and the wheel increases toward the outer peripheral side, and accordingly, the protrusion height of the protrusion and the thickness of the buffer member also increase toward the outer peripheral side. Torque can be transmitted efficiently by equalizing.

In the invention described in claim 6, each of the projecting portions faces a coupling portion (for example, the sprocket coupling portion 77 of the embodiment) for the sprocket (for example, the driven sprocket 31 of the embodiment) of the sprocket mounting portion, It has the recessed part (for example, recessed part 85 of an Example) which avoids this connection part, It is characterized by the above-mentioned.
According to this structure, workability | operativity at the time of couple | bonding or disassembling a sprocket and a sprocket attachment part improves.

  According to a seventh aspect of the present invention, in the sprocket holding portion structure of the chain type power transmission mechanism (for example, the chain type power transmission mechanism 50 of the embodiment) of a vehicle (for example, the motorcycle 1 of the embodiment), the sprocket holding portion (for example, The driven flange 70) of the embodiment connects a sprocket mounting portion (for example, the sprocket mounting portion 72 of the embodiment), a wheel mounting portion (for example, the wheel mounting portion 73 of the embodiment), and the sprocket mounting portion and the wheel mounting portion. A connecting portion (for example, the connecting wall portion 74 of the embodiment), and the connecting portion is recessed from the inner peripheral end of the wheel mounting portion to the outer peripheral side (for example, the thinned portion 74a of the embodiment). ).

  According to this configuration, in addition to the function and effect of the first aspect, the connecting portion between the sprocket mounting portion and the wheel mounting portion can be made into a thin-walled structure while maintaining necessary rigidity.

According to the first, second, and third aspects, the vehicle weight can be reduced by reducing the weight of the sprocket holding portion.
According to the fourth and fifth aspects of the present invention, torque can be efficiently transmitted to the wheel via the buffer member.
According to the sixth aspect of the present invention, it is possible to improve the maintainability of the vehicle by improving the sprocket coupling and disassembling workability.
According to the invention described in claim 7, it is possible to reduce the weight while maintaining the rigidity of the sprocket holding portion.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the directions such as front, rear, left and right in the following description are the same as those in the vehicle unless otherwise specified. In addition, an arrow FR appropriately shown in the drawing indicates the front of the vehicle, an arrow LH indicates the left side of the vehicle, and an arrow UP indicates the upper side of the vehicle.

  As shown in FIG. 1, left and right front forks 3 that pivotally support a front wheel 2 of a motorcycle (vehicle) 1 are pivoted to a head pipe 6 provided at a front end portion of a vehicle body frame 5 via a steering stem 4 so as to be steerable. The swing arm 8 that is supported and pivotally supports the rear wheel 7 is pivotally supported by a left and right pivot portion 9 provided at an intermediate portion of the vehicle body frame 5 at its front end. The vehicle body frame 5 is a so-called double cradle type in which a pair of main frames 10 and a down tube 11 branching from the head pipe 6 and extending to the left and right are coupled in the vicinity of the respective pivot portions 9. A water-cooled parallel four-cylinder engine 12, which is a prime mover of the motorcycle 1, is mounted at the center of the vehicle body surrounded by the main frames 10 and the down tubes 11. Front end portions of the left and right seat rails 13 are coupled to the upper rear side of each main frame 10, and left and right side pipes 14 extending obliquely upward and rearward from the vicinity of the pivot portion 9 at the substantially middle portion of each seat rail 13. The upper ends of each are joined. Between the connecting portions of the side pipes 14 and the seat rails 13 and the left and right arm bodies 8a of the swing arm 8, left and right rear cushions 15 are disposed.

  The cylinder portion 16 of the engine 12 is disposed on the crankcase 17 in a slightly tilted state. A downstream side of the throttle body 18 corresponding to each cylinder is connected to the rear portion of the cylinder portion 16, and an upstream side of each throttle body 18 is connected to an air cleaner case 19. An exhaust pipe 20 corresponding to each cylinder is connected to the front part of the cylinder part 16, and the exhaust pipes 20 are gathered together while passing through the front and the lower side of the crankcase 17 and arranged on the right side of the rear part of the vehicle body. Connected to the silencer 21 made. A radiator 22 for cooling the engine 12 is disposed in front of the engine 12 with the exhaust pipes 20 interposed therebetween.

  A fuel tank 23 is supported on each main frame 10 from above, and a seat 24 is supported on the front portion of each seat rail 13 from above. Left and right steps 25 are attached to the vicinity of each pivot portion 9, and left and right handles 26 are attached to the top of each front fork 3. A brake caliper 28 is attached to the lower part of each front fork 3, and left and right brake rotors 29 corresponding to each brake caliper 28 are attached to the hub portion of the front wheel 2 to constitute left and right front disc brakes 30. The A rear disc brake (not shown) having the same configuration as that of the front disc brake 30 is disposed on the right side of the rear wheel 7.

A driven sprocket 31 is disposed on the left side of the rear wheel 7, and a drive chain 33 is endlessly wound around the driven sprocket 31 and a drive sprocket 32 disposed on the rear left side of the engine 12. The chain type power transmission mechanism 50 is configured, and the driving force of the engine 12 is transmitted to the rear wheel 7 via the chain type power transmission mechanism 50.
A front cowl 34 as a windshield covering the periphery of the head pipe 6 is attached to the front part of the body frame 5, and an under cowl that covers the lower part of the down tube 11 and covers the lower part of the engine 12 from below. 35 is mounted, and a side cover 36 that covers the upper rear side of each main frame 10 from the side is mounted on both sides of the center of the vehicle body frame 5, and the rear portion of each seat rail 13 is mounted on the rear of the vehicle body frame 5 from above. A rear cowl 37 is attached to cover the vehicle.

  As shown in FIG. 7, the rear cowl 37 is made of, for example, FRP (Fiber Reinforced Plastics), and is formed by integrally forming an upper wall portion 38 and both side wall portions 39. Is provided so that the front end portion thereof is continuous with the rear end portion of the seat 24. Here, the seat 24 is formed integrally with a rear pad portion 24b that rises obliquely rearward and upward at a rear end portion of a seat body 24a on which an occupant sits, and the rear end portion of the seat 24 extends along the rear pad portion 24b. The upper side is inclined so as to be located rearward. The front end of the upper wall 38 of the rear cowl 37 is connected to the upper edge of the rear pad 24b of the seat 24, and the front ends of the side walls 39 of the rear cowl 37 are connected to the rear end of the rear pad 24b and the seat body 24a. It is a series.

  The upper wall portion 38 of the rear cowl 37 has a substantially trapezoidal appearance that is symmetrical in the left-right direction that narrows the width in the rear view, and is inclined slightly rearward in the side view. The side wall portions 39 include an upper edge portion 39a along both side edge portions 38a of the upper wall portion 38 in a side view, and a lower edge portion 39b extending substantially obliquely downward and forward from the rear end portion of the upper edge portion 39a. And a front and back edge portion 39c along the rear end portion of the seat 24 has a relatively long triangular shape. The rear portions of the seat rails 13 extending obliquely upward and rearward are disposed inside the both side wall portions 39 of the rear cowl 37, and the rear end portion of the rear cowl 37 has a lens surface inclined upward. A tail lamp unit 41 is provided.

  Here, in a saddle-ride type vehicle such as the motorcycle 1 having the rear cowl 37 at the rear of the seat 24, an increase in down force (the force of air that pushes the vehicle body downward) is increased by using aerodynamic force acting on the rear cowl 37. There are things to plan.

That is, side wing portions 42 that are inclined rearward are formed on both side wall portions 39 of the rear cowl 37 by projecting portions along the lower edge portions 39a outward in the vehicle width direction. Further, a rear wing portion 43 is formed on the upper wall portion 38 of the rear cowl 37 so that its rear edge portion protrudes obliquely upward and rearward. The rear end portions of the side wing portions 42 are connected to both end portions of the rear wing portion 43, whereby the wing portions 42 and 43 are continuously provided so as to draw a substantially U-shape that opens forward in a top view. .
When each of the wing portions 42 and 43 receives the traveling wind, a force for pressing the rear cowl 37 and the rear portion of the vehicle body downward is generated, and the grip force of the front and rear wheels 2 and 7 can be increased. It becomes.

  By the way, particularly when the occupant wakes up, such as during turning, negative pressure and turbulence are generated above the rear cowl 37, that is, behind the occupant seated on the seat 24. Since such negative pressure and turbulent flow have a large influence on the aerodynamic force acting on the rear cowl 37, there is a demand for improvement in order to stabilize the aerodynamic force.

  Therefore, in the motorcycle 1 having the rear cowl 37 behind the seat 24 in order to suppress the negative pressure and turbulence generated behind the passenger and improve the aerodynamic stability of the rear cowl 37, the upper wall portion 38 of the rear cowl 37 is provided. In addition, a communication portion 44 for communicating the space above and below the upper wall portion 38 is provided.

The communication portion 44 has an opening 45 formed in a substantially trapezoidal shape with a width that becomes narrower toward the rear side in a top view so that the communication portion 44 is substantially similar to the upper wall portion 38, and a mesh attached to the opening 45 from the lower surface side of the upper wall portion 38. And a sheet 46. The mesh sheet 46 is composed of a relatively fine wire mesh, and a plurality of locations (3 × 3 total 9 locations) on the outer periphery thereof are fixed to the outer periphery of the opening 45 by rivets 47.
In other words, the communication portion 44 is positioned between the seat rails 13 in a top view, and its front edge is separated from the rear end of the seat 24 by a predetermined amount, and the rear edge is positioned near the front end of the tail lamp unit 41. It is provided so as to be positioned closer to the rear end of the rear cowl 37 while ensuring a predetermined opening area.
Here, the motorcycle 1 is a racing vehicle, and a rear fender or the like is not disposed in the rear cowl 37. Therefore, the upper space 38 and the lower space of the upper wall portion 38 of the rear cowl 37 are directly communicated with each other by the communication portion 44. .

  According to this configuration, air flows above and below the rear cowl 37, and it becomes possible to cancel the negative pressure and turbulence generated above the rear cowl 37, that is, behind the occupant seated on the seat 24. The aerodynamic stability is improved, and a good downforce can be obtained. In particular, when applied to a lightweight racing vehicle such as the motorcycle 1, the effect is high. Moreover, the opening 45 can be made inconspicuous by the mesh sheet 46, and the appearance can be maintained well. The communication portion 44 is not limited to the above-described one, and the shape, position, and number of installations are arbitrary, and a large number of through holes are formed in the upper wall portion 38 instead of the combination of the opening 44 and the mesh sheet 46. It may be a thing.

As shown in FIG. 2, at the rear end of each arm body 8 a of the swing arm 8, both end portions of the rear axle 51 passing through the center of the rear wheel 7 along the axis C parallel to the left-right direction (vehicle width direction). Is supported. For convenience of illustration, FIG. 2 shows only the parts on the left side of the vehicle.
A collar assembly 52 that penetrates the arm main body 8a in the vehicle width direction is attached to the rear end of each arm main body 8a. The collar assembly 52 is attached to a collar main body 53 having a flange portion 53a at the inner end in the vehicle width direction so as to penetrate the rear end of the arm main body 8a from the inner side in the vehicle width direction. A lock nut 54 is screwed and fixed to the outer peripheral portion of the tip of the collar body 53 protruding outward in the vehicle width direction. The outer end in the vehicle width direction of the collar assembly 52 forms a head surface of the rear axle 51 and a seating surface of an axle nut (not shown).

  On the other hand, the rear axle 51 is formed by reducing the diameter of both ends of the hollow axle body 51a and engraving a thread on the outer periphery thereof. For example, a sleeve nut 51b is screwed and fixed to the left end of the rear axle 51. A head is formed and an axle nut can be screwed to the right end. Such a rear axle 51 is attached from the left side of the swing arm 8 so as to penetrate the rear end portion of each arm body 8a together with the collar assembly 52, and is projected to the front end portion of the rear axle 51 protruding to the right side of the swing arm 8. Axle nuts are screwed and can be tightened.

  Referring also to FIG. 3, the rear wheel 7 has a tire 7 a mounted on a rim portion 55 a of a rear wheel 55, and a cylindrical wheel hub portion 56 is provided at the center of the rear wheel 55. The wheel hub portion 56 and the rim portion 55a are integrally formed through a plurality of spoke portions 55b. A hub main body 57 projecting outward in the vehicle width direction is integrally formed on both sides of the wheel hub portion 56, and a main ball bearing 58 is press-fitted into the hub main body 57. A stopper wall 57a that abuts against the outer race of the main ball bearing 58 and defines the relative position in the vehicle width direction is provided at the inner end of the hub body 57 in the vehicle width direction. A lock nut 57b that clamps and fixes the outer race of the main ball bearing 58 together with the stopper wall 57a is screwed to the end portion on the outer side in the direction. A rear axle 51 is inserted into the main ball bearing 58, and the rear axle 51 rotatably supports the hub body 57 and the rear wheel 7 via the main ball bearing 58.

  A chain adjuster 61 that adjusts the play of the drive chain 33 is provided at the rear end of each arm body 8a. The chain adjuster 61 includes an adjuster main body 62 that sandwiches the rear end portion of the arm main body 8a inside and outside in the vehicle width direction, and an adjustment bolt 63 provided at the rear end portion of the adjuster main body 62. The adjuster body 62 can be moved back and forth by increasing or decreasing the tightening amount. The tip of the adjuster main body 62 is engaged with the collar assembly 52 by penetrating the collar assembly 52. The adjuster main body 62 is driven by the collar assembly 52, the rear axle 51 penetrating the collar assembly 52, and the coaxial assembly. By moving together with the sprocket 31, the play of the drive chain 33 can be adjusted. A recess 62a that forms a seating surface of the lock nut 54 of the collar assembly 52 is provided on the outer side in the vehicle width direction of the adjuster main body 62. The lock nut 54 and the rear axle 51 are provided on the outer side in the vehicle width direction of the recess 62a. An axle end cover 64 that covers the head (or axle nut) is attached. An opening 64a is formed at the center of the axle end cover 64, and the tip of the resin cap 65 that closes the end opening of the rear axle 51 protrudes outward in the vehicle width direction from the opening 64a.

  The rear axle 51 is inserted into the center distance collar 66 in the wheel hub portion 56. The position of the center distance collar 66 in the vehicle width direction is defined by abutting both ends of the center distance collar 66 against the inner race of the main ball bearing 58. A side distance collar 67 is arranged on the outer side of the inner race of the main ball bearing 58 in the vehicle width direction, and the first and second auxiliary ball bearings 68a and 68b adjacent to each other are arranged on the outer side of the side distance collar 67 in the vehicle width direction. An inner race is arranged, and a side collar 69 is arranged on the outer side in the vehicle width direction of the inner race of the second secondary ball bearing 68b located on the outer side in the vehicle width direction. A flange portion 53a of the assembly 52 is disposed.

  From both ends of the center distance collar 66, a thin sleeve portion 66a having the same inner peripheral surface is extended outward in the vehicle width direction, and the sleeve portion 66a extends to the main ball bearing 58, the side distance collar 67, and each width. It is inserted into the ball bearing and the side collar 69. Further, from the inner end of the side collar 69, a thin sleeve portion 69a having the same inner peripheral surface extends inward in the vehicle width direction, and the sleeve portion 69a is inserted into each width ball bearing. As a result, the main ball bearing 58, the side distance collar 67, and the side collar 69 are supported by the rear axle 51 via the sleeve portion 66a of the center distance collar 66, and the auxiliary ball bearings 68a and 68b are the sleeves of the center distance collar 66. It is supported by the rear axle 51 via the portion 66 a and the sleeve portion 69 a of the side distance collar 67.

  Between the head of the rear axle 51 and the axle nut, the collar assembly 52, the side collar 69, the inner race of each auxiliary ball bearing 68a, 68b, the side distance collar 67, and the inner race of the main ball bearing 58 are arranged in this order from the left side. The center distance collar 66 and the inner race and the collar assembly 52 of the main ball bearing 58 on the right side of the vehicle body are disposed on the axis C, and these are tightened to the rear axle 51 and the axle nut, so that the center distance collar 66 and the collar assembly 52 are in a specified position on the axis C. The rear axle 51 is supported in an arrayed state, and both ends of the rear axle 51 are supported by the rear end of the swing arm 8. A driven flange (sprocket holding portion) 70 that holds the driven sprocket 31 is disposed between the left arm main body 8 a and the wheel hub portion 56.

The driven flange 70 is for engaging the rear wheel 7 and the driven sprocket 31 via a plurality of damper rubbers (buffer members) 71 so as to be able to transmit torque, and the sprocket mounting portion 72 sharing the axis C and the wheel mounting. The portion (engagement portion) 73 is integrally connected via a cylindrical connection wall portion (connection portion) 74 that also shares the axis C.
The driven sprocket 31 has a disk shape with an open central portion, and a plurality of teeth 31a are formed on the outer peripheral portion thereof, and six bolts 81 for coupling with the driven flange 70 can be inserted on the inner peripheral portion thereof. The bolt insertion holes 31b are formed at equal intervals on a circumference around the axis C. Hereinafter, the direction along the circumference around the axis C will be referred to as the circumferential direction, and the direction along the diameter of the circumference will be described as the radial direction.

 As shown in FIGS. 4 and 6, the sprocket mounting portion 72 in the driven flange 70 includes a disc-shaped flange main body 75 having an open central portion, and a cylindrical flange hub portion 76 provided on the inner peripheral side of the flange main body 75. And six sprocket coupling portions 77 provided so as to protrude radially outward from the outer edge of the flange main body 75, and a short provided in an annular shape along the outer periphery of the flange main body 75 on the outer side in the vehicle width direction of the flange main body 75. The rib portion 78 and six reinforcing rib portions 79 provided so as to extend along the radial direction across the short rib portion 78 and the flange hub portion 76 are integrally formed.

 The auxiliary ball bearings 68a and 68b are press-fitted into the flange hub portion 76, and the flange hub portion 76 and the driven flange 70 can be rotated together with the outer race of the auxiliary ball bearings 68a and 68b. As a result, the flange hub portion 76 and the driven flange 70 are rotatably supported by the rear axle 51 via the auxiliary ball bearings 68a and 68b. At the end of the flange hub portion 76 on the inner side in the vehicle width direction, the axis of each of the auxiliary ball bearings 68a, 68b including and contacting the outer race of the first auxiliary ball bearing 68a on the inner side in the vehicle width direction. A stopper wall 76a that defines the relative position in the direction is formed.

 Each sprocket coupling portion 77 is provided at equal intervals in the circumferential direction corresponding to each bolt insertion hole 31 b of the driven sprocket 31, and the coupling bolt 81 can be inserted into each sprocket coupling portion 77. Bolt insertion holes 77a are formed. The short rib portion 78 can be fitted to the outer periphery of the driven sprocket 31 so that the outer periphery thereof is aligned with the inner periphery of the central opening. Further, the reinforcing rib portions 79 are provided so as to be positioned on the inner peripheral side of the sprocket coupling portions 77, that is, at equal intervals in the circumferential direction.

 The driven sprocket 31 is attached to the sprocket mounting portion 72 of the driven flange 70 from the outside in the vehicle width direction, the short rib portion 78 is fitted to the central opening thereof, and the relative positions of the bolt insertion holes 31b and 77a are aligned. Further, the coupling bolt 81 is inserted into each of the bolt insertion holes 31b and 77a from the inner side in the vehicle width direction, and the coupling nut 82 is screwed into the bolt from the outer side in the vehicle width direction to tighten them. And the driven sprocket 31 are integrally coupled (see FIG. 2).

  On the inner side in the vehicle width direction of the flange main body 75 (on the rear wheel 55 side), the connecting wall portion 74 having a cylindrical shape having a smaller diameter than the flange main body 75 is provided projecting inward in the vehicle width direction. The connecting wall portion 74 is formed integrally with the flange main body 75, has a substantially uniform thickness in the radial direction, and the thickness is sufficiently thin relative to its own radius. The wheel mounting portion 73 is integrally formed on the leading end side of the connecting wall portion 74.

As shown in FIGS. 5 and 6, the wheel mounting portion 73 includes a disc-shaped base portion (disc-like portion) 83 having an open central portion, and six dampers protruding from the base portion 83 toward the inside in the vehicle width direction. A boss (projection) 84 is formed integrally.
The base portion 83 has a central opening and an outer peripheral shape that is slightly larger than the flange main body 75 of the sprocket mounting portion 72. The base portion 83 has a belt shape having a predetermined width that is continuous in an annular shape. The tip of the connecting wall 74 is connected from the outside in the vehicle width direction. Here, in the driven flange 70, it can be said that the base part 83, the connection wall part 74, and the flange main body 75 form a thin-walled structure that penetrates the inside of the cylinder. In other words, on the inner peripheral side of the connecting wall portion 74, a thinned portion 74a that is recessed from the inner peripheral end of the base portion 83 toward the outer peripheral side is formed over the entire periphery.
Further, the base portion 83 is positioned on the outer side in the vehicle width direction from the inner peripheral side toward the outer peripheral side, in other words, from the rear wheel 55 toward the outer peripheral side in the vehicle width direction (axial direction). It is formed in a tapered shape that is gently inclined so as to be separated.

  The damper bosses 84 are provided at equal intervals in the circumferential direction, and are arranged so as to overlap the sprocket coupling portions 77 in the axial direction. Moreover, each damper boss | hub 84 is provided so that it may have a fixed cross-sectional shape along an axial direction. Here, when viewed in the axial direction, each damper boss 84 is provided so as to be line-symmetric with respect to the center line D along the radial direction, and the bolt insertion hole 77a of each sprocket coupling portion 77 on the center line D. It is provided so that the center is located. The damper bosses 84 are provided so that both side surfaces in the circumferential direction are parallel to the radial direction, and are provided so as to cross the inner and outer edges of the base portion 83 in the radial direction. Each damper boss 84 forms a tip surface along a plane orthogonal to the axis C.

  Here, when viewed in the axial direction, the center of the bolt insertion hole 77a of each sprocket coupling portion 77 is located on the outer edge of the base portion 83, and the connection to the coupling bolt 81 inserted through each such bolt insertion hole 77a. In order to facilitate the work, the outer peripheral portion of the wheel mounting portion 73 is cut out at the outer peripheral portion of the base portion 83 and the outer peripheral portion of each damper boss 84 so as to avoid the bolt insertion hole 77a corresponding to the axial view. Six recesses 85 are provided which are recessed inward in the radial direction.

  Also, here, each damper boss 84 is provided so as to extend substantially over the inner and outer peripheries of the base portion 83, and both side wall portions 86 respectively forming the both side surfaces, and over the inner peripheral side end of each side wall portion 86. The inner peripheral wall portion 87 provided in an arc shape along the circumferential direction, the outer peripheral wall portion 88 provided in a wave shape so as to form the concave portion 85 across the outer peripheral side ends of the both side wall portions 86, and the diameters of the both side wall portions 86 The central wall 89 provided in a circular arc shape along the circumferential direction across the central portion in the direction, and the central portion in the circumferential direction of the central wall portion 89 and the central portion in the circumferential direction of the outer peripheral wall portion 88 are connected. The hollow structure is formed with a plurality of lightening portions 92a, 92b, and 92c that are open to the inside in the vehicle width direction so as to leave the connecting wall portion 91 to be left.

Each of the damper bosses 84 enters the engagement groove portion 93 provided around the hub main body 57 on the left side portion of the wheel hub portion 56.
As shown in FIG. 2, the engagement groove portion 93 includes an inner peripheral wall portion 94 formed integrally with the outer periphery of the hub main body 57, and an outer peripheral wall portion provided at a predetermined distance from the radial outer side of the inner peripheral wall portion 94. 95 and a bottom wall portion 96 provided over the inner peripheral wall portion 94 and the outer peripheral wall portion 95 on the inner end in the vehicle width direction, and open to the outer side in the vehicle width direction. And provided on the outer periphery of the hub body 57 over the entire circumference. Note that the bottom wall portion 96 of the engagement groove portion 93 forms a bottom surface along a plane orthogonal to the axis C. In a state in which each damper boss 84 enters the engagement groove portion 93, the engagement between the inner and outer peripheral surfaces of each damper boss 84 and the inner and outer peripheral surfaces of the engagement groove portion 93 and the front end surface of each damper boss 84. A substantially constant gap is formed between the bottom surface of the joint groove portion 93.

  Referring also to FIG. 3, six groove inner ribs 97 along the radial direction and the axial direction are provided in the engagement groove portion 93 at equal intervals in the circumferential direction. Each groove inner rib 97 is provided so as to straddle the inner and outer peripheral wall portions 94 and 95 of the engagement groove portion 93 and the bottom wall portion 96, and torque output to the rear wheel 7 and torque input from the rear wheel 7 can be performed. Is done. Each of the in-groove ribs 97 is provided with a damper rubber 71.

  Each damper rubber 71 is formed by forming a slit that can be fitted into the groove rib 97 in a block material made of, for example, EPDM (ethylene propylene diene monomer) over the inner and outer circumferences of the engagement groove portion 93. In a state where each of the damper rubbers 71 is mounted on each of the groove inner ribs 97, each of the damper bosses 84 is brought into contact with the side surface of the adjacent damper rubber 71 so that both side surfaces in the circumferential direction are in contact with each other. 93. As a result, the driven flange 70 and the wheel hub are engaged in the rotational direction, and torque can be transmitted between these via the damper rubber 71.

  Each damper rubber 71 is provided so as to be generally aligned in a space formed by closing the engagement groove 93 with the base 83 of the wheel mounting portion 73. At this time, the base 83 is disposed on the inner peripheral side. From the rear wheel 55 to the outer peripheral side, the distance between the bottom surface of the engagement groove portion 93 and the upper surface of the base portion 83 increases toward the outer peripheral side. Accordingly, each of the damper bosses 84 is provided to increase its protruding height toward the outer peripheral side, and each damper rubber 71 is provided to increase its thickness toward the outer peripheral side.

  As described above, in the driven flange structure of the chain type power transmission mechanism 50 of the motorcycle 1 in the above embodiment, the driven flange 70 has the sprocket mounting portion 72 and the wheel mounting portion 73, and these sprocket mounting portions 72. And the wheel mounting portion 73 are connected by a connecting wall portion 74 as a thin-walled structure that penetrates the inside of the cylinder, so that the weight of the driven flange 70 can be reduced, and the weight of the motorcycle 1 can be reduced. Can be reduced.

  In the driven flange structure, the wheel mounting portion 73 has a plurality of damper bosses 84 that engage with the wheel hub portion 56 of the rear wheel 55 via the damper rubber 71 on the disc-shaped base portion 83. As a result, the base portion 83 becomes a thin structure, and the driven flange 70 can be further reduced in weight.

  Further, in the above-described driven flange structure, each of the damper bosses 84 is provided with the respective thinned portions 92a, 92b, and 92c, so that the plurality of damper bosses 84 become a hollow (thin wall) structure, and the driven flange 70 is further reduced in weight. Can be achieved.

  Here, in the driven flange structure, the damper bosses 84 are arranged on the base portion 83 so as to be able to transmit torque efficiently while maintaining the shock absorbing performance of the damper rubbers 71 while suppressing the amount of bending. Six are arranged side by side at equal intervals in the direction.

  Moreover, in the driven flange structure, the disc-shaped base portion 83 is provided so as to be inclined away from the rear wheel 55 in the axial direction from the inner peripheral side toward the outer peripheral side. The distance from the wheel increases toward the outer periphery, and accordingly, the protrusion height of the damper boss 84 and the thickness of the damper rubber 71 also increase toward the outer periphery. Therefore, the torque generated by the damper rubber 71 is equalized. Can be transmitted efficiently.

The present invention is not limited to the above-described embodiment. For example, the connecting wall 74 may be a polygonal tube (in other words, a thin-walled structure that penetrates the inside of a polygonal column) instead of a cylindrical shape. The outer peripheral surface may be a cylindrical surface or a polygonal surface, while the inner peripheral surface may be a polygonal surface or a cylindrical surface. Moreover, the thing which gave the hollow shape, such as forming a step shape and a recessed part in the outer peripheral side of the connection wall part 74, may have a hollow hole penetrated inside and outside. Moreover, for example, ribs or the like that partition the circumferential portion in the thinned portion 74a in the connecting wall portion 74 may be provided.
Further, the shape and number of the damper bosses 84 may be appropriately changed according to the diameters of the driven flange 70 and the wheel hub portion 56 and the magnitude of the transmission torque.
And the structure in the said Example is an example, and it cannot be overemphasized that a various change is possible in the range which does not deviate from the summary of invention, as well as being not limited to the application to a motorcycle.

1 is a side view of a motorcycle according to an embodiment of the present invention. It is AA sectional drawing in FIG. It is a disassembled perspective view of the main components around a driven flange. It is the side view which looked at the driven flange from the sprocket attachment part side. It is the side view which looked at the driven flange from the wheel attachment part side. It is BB sectional drawing in FIG. (A) is a side view around a rear cowl, and (b) is a top view of (a).

Explanation of symbols

1 Motorcycle (vehicle)
31 Driven sprocket
50 Chain type power transmission mechanism 55 Rear wheel (wheel)
70 Driven flange (sprocket holding part)
71 Damper rubber (buffer member)
72 Sprocket attachment part 73 Wheel attachment part 74 Connection wall part (thin structure, connection part)
74a Meat removal part 77 Sprocket joint part (joint part)
83 Base part (disc-shaped part)
84 Damper boss (projection)
85 Recesses 92a, 92b, 92c

Claims (7)

In a sprocket holding part structure of a chain type power transmission mechanism of a vehicle, the sprocket holding part has a sprocket attaching part and a wheel attaching part, and the sprocket attaching part and the wheel attaching part are pierced through the inside of the cylinder. A sprocket holding part structure characterized by being connected by a thin-walled structure. The sprocket holding part structure according to claim 1, wherein the wheel mounting part has a plurality of protrusions that engage with the wheel via a buffer member on the disk-like part. The sprocket holding part structure according to claim 2, wherein a thinning part is provided in each of the protrusions. 4. The sprocket holding part structure according to claim 2, wherein six of the protrusions are arranged on the disk-like part at equal intervals in the circumferential direction. 5. The sprocket holding part structure according to any one of claims 2 to 4, wherein the disk-shaped part is provided so as to be inclined away from the wheel as it goes from the inner circumference side toward the outer circumference side. . The sprocket holding device according to any one of claims 2 to 5, wherein each of the protrusions has a recess that avoids the coupling portion at a portion facing the coupling portion for the sprocket of the sprocket mounting portion. Part structure. In a sprocket holding part structure of a chain type power transmission mechanism of a vehicle, the sprocket holding part has a sprocket attachment part, a wheel attachment part, and a connecting part that connects the sprocket attachment part and the wheel attachment part. The sprocket holding portion structure is characterized in that the connecting portion has a hollow portion that is recessed from the inner peripheral end of the wheel mounting portion toward the outer peripheral side.

Images