JP4572632B2 - Rear swing arm of motorcycle - Google Patents

Description

  The present invention relates to a rear swing arm of a motorcycle.

  As a means for suspending the rear wheel of the motorcycle, a rear swing arm is generally used. The rear swing arm has a front end pivotally attached to a body frame via, for example, a pivot shaft, and pivotally supports a rear wheel on a rear end that is a free end.

  As an example of the structure of the rear swing arm, for example, there is a structure in which a pair of left and right arms are connected to a rear part of a main body that is triangular in a side view. Further, this arm portion is formed in a V shape formed in a side view composed of a main arm and a sub arm, and its open end is connected to the rear portion of the main body, and the entire rear swing arm is formed in a triangular shape protruding upward in a side view. There is something. (For example, refer to Patent Document 1).

Further, there is a casting method as a manufacturing method of the rear swing arm. (For example, refer to Patent Document 2).
Japanese Patent Publication No. 5-81478 JP 2002-225777 A

  However, if the arm part, which forms the rear part of the rear swing arm and the main arm and the sub arm are formed in a V shape when viewed from the side, is formed by casting or forging integrally, the tip is open when viewed from the side. The member may be distorted during molding and heat treatment.

  In addition, when the main body constituting the front half of the rear swing arm is formed in a box shape for weight reduction, for example, a partition wall may be provided to partition the interior up and down in order to obtain sufficient strength. If the body is molded by casting, it is necessary to provide a large hole in the partition wall for core support and core sand removal, and it is necessary to increase the thickness of each part of the member to compensate for the resulting strength deficiency For example, an increase in weight is inevitable.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a rear swing arm of a motorcycle that has a simple structure and high distortion accuracy with low distortion while ensuring sufficient strength. To do.

In order to solve the above-described problems, a rear swing arm of a motorcycle according to the present invention includes a rear swing arm pivotally attached to a vehicle body frame via a pivot shaft as described in claim 1. It is composed of a main body in the front half formed in a substantially triangular shape in side view and a pair of left and right arm parts in the rear half, and these arm parts are further provided with axle support parts that pivotally support the axles of the rear wheels at the rear end. A main arm portion provided and a sub arm portion extending from the rear end portion of the main arm portion toward either the diagonally forward upper side or the diagonally lower front side. The arm portion has a substantially U-shaped cross section. The outer half and the inner half are divided and formed, and the front end portions of the main arm portion and the sub arm portion of at least one of the half portions are connected to each other by a bridge portion. And, while casting molding the main body in a hollow integral box-partition up and down inside the main body by a partition wall, right and left rear end of the main body in which the bridge portion of the arm portion of the right and left are connected The upper space and the lower space inside the main body, which are partitioned by the partition wall in the upper and lower parts, form opening holes that communicate with the outside, and the bridge portion of the arm part is closed so as to close these opening holes. Connected .

In order to solve the above-described problem, as described in claim 2 , the partition wall inside the main body is extended to either one of the upper side wall and the lower side wall of the main arm part of the arm part. It was formed along.

In order to solve the above-described problem, as described in claim 3 , the bridge portion and the axle support portion formed on the arm portion are cast or forged into a half on the same side. One of them is integrally formed.

  According to the rear swing arm of the motorcycle according to the present invention, the rigidity of the arm portion alone is improved, and the distortion of the member during molding and heat treatment is reduced, and the component accuracy is improved. Further, since the dimensional accuracy of the rear swing arm is improved, the steering stability of the motorcycle is improved.

  Furthermore, since automatic welding work by a robot or the like is possible, it is possible to reduce costs and to provide a large hole in the partition wall for supporting the core and removing the core sand, which were conventionally required. As a result, the effect of reinforcing the main body by the partition wall is enhanced, and sufficient strength can be secured with the minimum wall thickness, so that the weight can be reduced.

  Furthermore, the thickness of the portion where the strength of one half is required can be partially changed and reinforced, and the other half can be formed of a simple plate material, thereby reducing the manufacturing cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a left side view showing an example of a motorcycle to which the present invention is applied. As shown in FIG. 1, the motorcycle 1 has a body frame 2, and a head pipe 3 is provided at the front end thereof. The head pipe 3 is provided with a suspension mechanism (not shown) and is provided with a steering mechanism 7 including a pair of left and right front forks 5 and a handle bar 6 that rotatably supports the front wheel 4. Is steered so as to be pivotable left and right.

  The main frame 8 constituting the vehicle body frame 2 is, for example, of a twin tube type, and is expanded in the left-right direction immediately after the head pipe 3 and then extends substantially linearly in a side view obliquely downward and rearward in parallel with each other. A pair of left and right tank rails 9 and a pair of left and right center frames 10 connected to the rear ends of the tank rails 9 and extending substantially downward. Also, seat rail mounting bosses 11 are formed at the rear end portions of the left and right tank rails 9, and the front end portions of the pair of left and right seat rails 12 that are formed wide in the vertical direction in a side view. The upper edge is attached in a state of being inclined forward and downward and extends obliquely upward and rearward.

  A fuel tank 13 is detachably mounted above the tank rail 9, and an operation seat 14 is detachably disposed above the seat rail 12, for example. In addition, a pivot shaft 15 is installed substantially at the center of the center frame 10, and a rear swing arm 16 is pivotally attached to the pivot shaft 15 so as to be swingable about the pivot shaft 15, and a rear end of the rear swing arm 16. The rear wheel 17 is pivotally supported in a freely rotatable manner. An engine 18 is disposed below the center of the vehicle body between the front and rear wheels 4 and 17 and below the fuel tank 13.

  A throttle body 19 is connected above the engine 18, and an air cleaner 20 is connected to the upstream side of the throttle body 19. On the other hand, an exhaust pipe 21 is connected to the front portion of the engine 18. The exhaust pipe 21 extends downward from the front part of the engine 18 and further extends rearward, and a muffler 22 is connected to the downstream end thereof.

  The motorcycle 1 is partially covered with a streamlined cowling 23 to reduce air resistance during travel and to protect a rider (not shown) from travel wind pressure. The cowling 23 is composed of a plurality of parts, and mainly includes a front cowling 24 that covers the front upper part of the vehicle body, a lower cowling 25 that covers from the lower part of the front cowling 24 to both sides of the engine 18, and the driving seat 14. And a seat tail cover 26 covering the rear part of the vehicle body from the lower rear part. Further, a gap between the lower part of the fuel tank 13 and the operation seat 14 and the vehicle body frame 2 is covered with a frame cover 27. Further, a rear fender 28 is provided below the operation seat 14 and the seat tail cover 26 above the rear wheel 17 so as to cover the rear wheel 17 from above. The covers such as the cowling 23 are formed of a material such as a synthetic resin.

  FIG. 2 is an enlarged left side view of the rear swing arm 16, and FIG. 3 is an enlarged plan view of the rear swing arm 16. 4 is a perspective view of the rear swing arm 16 as viewed from the diagonally lower left side, and FIG. 5 is a perspective view of the rear swing arm 16 as viewed from the diagonally lower right side.

  As shown in FIGS. 2 to 5, the rear swing arm 16 constitutes a front half of the rear swing arm 16, a main body 29 formed in a substantially triangular shape in side view, and a rear half of the rear swing arm 16. And a pair of left and right arm portions 30R, 30L.

  The arm portions 30R and 30L include main arm portions 33R and 33L having axle support portions 32 and 32 that pivotally support the axle 31 of the rear wheel 17 at the rear end portions, and rear ends of these main arm portions 33R and 33L. Sub-arm portions 34R and 34L extending from the upper portion toward the front obliquely upward (or may be obliquely lower and forward), and are formed in a substantially V shape in side view, and the main arm portions 33R and 33L and the sub-arm portions The front end portions of 34R and 34L are connected to the left and right rear end portions of the main body 29.

Further, the left and right arm portions 30R and 30L are each formed by being divided into outer halves 35R and 35L and inner halves 36R and 36L each having a substantially U-shaped cross section formed by casting or forging, for example. These half bodies 35R, 35L, 36R, and 36L have a structure. 6 is a perspective view of the inner half 36L of the left arm 30L , and FIG. 7 is a perspective view of the inner half 36R of the right arm 30R .

  In addition, at least one half of the outer halves 35R and 35L and the inner halves 36R and 36L, in this embodiment, all the halves 35R, 36R, except for the outer half 35L of the left arm 30L, The front end portions of the main arm portions 33R and 33L and the sub arm portions 34R and 34L of 36L are connected to each other by bridge portions 37R and 37L, and these bridge portions 37R and 37L are connected to the left and right rear end portions of the main body 29. Further, the bridge portions 37R and 37L and the axle support portions 32 and 32 are integrally formed by casting or forging on the same half halves 36R and 36L.

  8 is a view taken in the direction of arrow VIII in FIG. 2, and FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. As shown in FIGS. 2, 8, and 9, the main body 29 formed in a substantially triangular shape in a side view is cast into a box shape, for example, so as to be hollow and integrated. Further, the inside of the main body 29 is partitioned up and down by a reinforcing partition wall 38 formed along the extension line of the upper side walls (or lower side walls) of the main arm portions 33R and 33L of the arm portions 30R and 30L. .

  Furthermore, an upper space 39 and a lower space 40 inside the main body 29 that are vertically partitioned by a partition wall 38 at the left and right rear ends of the main body 29 to which the bridge portions 37R and 37L of the left and right arm portions 30R and 30L are connected. Are both formed with an opening 41 communicating with the outside. These opening holes 41 can be used for supporting a core (not shown) and removing core sand when casting the main body 29, and bridge portions 37R of the arm portions 30R, 30L so as to close the opening holes 41. 37L is connected.

  Next, the operation of this embodiment will be described.

  The rear swing arm 16 is composed of a main body 29 in the front half and arm portions 30R, 30L in the rear half, and these arm portions 30R, 30L are further supported at the rear end to support the axle 31 of the rear wheel 17. The main arm portions 33R and 33L including the portions 32 and 32, and the sub arm portions 34R and 34L extending from the rear end portions of the main arm portions 33R and 33L forward obliquely upward or obliquely downward to the front, The arm portions 30R, 30L are divided into outer halves 35R, 35L and inner halves 36R, 36L having a substantially U-shaped cross section, and at least one of the outer halves 35R, 35L and the inner halves 36R, 36L. The front end portions of the half main arm portions 33R and 33L and the sub arm portions 34R and 34L are connected to each other by bridge portions 37R and 37L. As a result, the rigidity of the arm portions 30R and 30L alone is improved, the distortion of the members at the time of molding and heat treatment is reduced, and the component accuracy is improved, so that the dimensional accuracy of the rear swing arm 16 is also improved, and the motorcycle The steering stability of 1 is also improved.

  Further, the bridge portions 37R and 37L that connect the front end portions of the main arm portions 33R and 33L and the sub arm portions 34R and 34L are connected to the left and right rear end portions of the main body 29, whereby the main body 29 and the arm portion 30R are connected. , 30L is simplified in shape and suitable for automatic welding work by a robot or the like, so that the welding work can be performed by an inexpensive method.

  Further, the inside of the main body 29, which is integrally cast in a box shape, is vertically divided by a partition wall 38, and the left and right rear ends of the main body 29 to which the bridge portions 37R, 37L of the left and right arm portions 30R, 30L are connected. The upper space 39 and the lower space 40 inside the main body 29 that are partitioned vertically by the partition wall 38 are formed with opening holes 41 that communicate with the outside, and the arm portions 30R so as to close these opening holes 41. , 30L bridge portions 37R, 37L are connected, for example, the space on the side to which the sub arm portions 34R, 34L side of the bridge portions 37R, 37L are connected, in this embodiment, the area of the opening hole 41 opened to the upper space 39 Can be formed in a size large enough to hold and discharge the core required to form the hollow space. It is no longer necessary to provide a large hole in the partition wall 38 for supporting the core and removing the core sand, and the reinforcing effect of the main body 29 by the partition wall 38 is enhanced, and sufficient strength is ensured with a minimum thickness. As a result, weight can be reduced.

  Furthermore, if the partition wall 38 inside the main body 29 is formed along the extension line of the upper side wall or the lower side wall of the main arm portions 33R, 33L of the arm portions 30R, 30L, the main body 29 can be more effectively reinforced. It becomes.

  The bridge portions 37R and 37L formed on the arm portions 30R and 30L and the axle support portions 32 and 32 are integrally formed by casting or forging on the same half halves 36R and 36L, so that a bridge that requires strength is required. The thickness of the portions 37R, 37L and the axle support portions 32, 32 can be partially changed for reinforcement. As a result, the other half bodies 35R and 35L can be formed of, for example, a simple plate material. Unlike parts for casting and forging, the thickness of the plate material cannot be partially changed, but the manufacturing cost can be reduced because the molding die is inexpensive.

1 is a left side view of a motorcycle showing an embodiment of a rear swing arm of the motorcycle according to the present invention. The enlarged left side of the rear swing arm. The enlarged plan view of a rear swing arm. The perspective view which looked at the rear swing arm from diagonally lower left. The perspective view which looked at the rear swing arm from diagonally lower right. The perspective view of the inner half of a left arm part. The perspective view of the inner side half body of a right arm part. The VIII arrow directional view of FIG. Sectional drawing which follows the IX-IX line of FIG.

Explanation of symbols

1 Motorcycle 2 Body frame 15 Pivot shaft 16 Rear swing arm 17 Rear wheel 29 Main body 30R, 30L Arm part 31 Rear wheel axle 32 Axle support part 33R, 33L Main arm part 34R, 34L Sub arm part 35R, 35L Outer half 36R, 36L Inner half bodies 37R, 37L Bridge portion 38 Partition wall 39 Upper space 40 Lower space 41 Opening hole

Claims (3)

A rear swing arm pivotably attached to a vehicle body frame via a pivot shaft is composed of a main body in the front half formed in a substantially triangular shape in side view and a pair of left and right arm parts in the rear half. A main arm portion provided with an axle supporting portion for pivotally supporting a rear wheel axle at the rear end portion of the arm portion, and extending from the rear end portion of the main arm portion toward either the front obliquely upward or the front obliquely downward direction. The arm portion is divided into an outer half body and an inner half body having a substantially U-shaped cross section, and the main arm of at least one of these half bodies the front end parts and the sub arm portion interconnected by a bridge portion, while casting molding the main body in a hollow integral box-shaped, up and down inside of the main body by a partition wall An opening through which the upper space and the lower space inside the main body, which are partitioned vertically by the partition wall at the left and right rear ends of the main body to which the bridge portion of the left and right arm portions is connected, communicates with the outside. A rear swing arm for a motorcycle, wherein a hole is formed and the bridge portion of the arm portion is connected so as to close the opening hole .
The rear swing arm of a motorcycle according to claim 1 , wherein the partition wall inside the main body is formed along an extension line of either the upper side wall or the lower side wall of the main arm part of the arm part. The rear swing arm of a motorcycle according to claim 1 or 2, wherein the bridge portion and the axle support portion formed on the arm portion are integrally formed on the same half on one side by at least one of casting or forging.

Images