JP4731926B2 - Motorcycle frame - Google Patents

Description

  The present invention relates to a motorcycle frame, and more particularly to a connection structure between a main frame and a pivot frame and a cross member.

As a motorcycle frame, there are a head pipe that supports a steering shaft to which a steering handle is attached at the top, a main frame that extends rearward from the head pipe, and a pivot frame that extends downward from the rear end of the main frame. Some are provided (see, for example, FIG. 2 of Patent Document 1). Further, as another form, it includes left and right main frames extending rearward from the head pipe, left and right pivot frames extending downward from the rear end portion of the main frame, and a cross member connecting between the left and right pivot frames. There is something. The front end of a swing arm that pivotally supports the rear wheel at the rear end is pivotally supported by one of the left and right pivot frames, and a suspension unit such as a shock absorber is interposed between the swing arm and the cross member. Is provided. Some suspension units are supported by the cross member via brackets attached to the cross member.
JP 2004-331001 A

  By the way, a large load is applied to the above-described main frame, pivot frame, and cross member. That is, since a heavy engine is suspended from the main frame and the pivot frame via the bracket, the engine load is applied to each frame. In addition, when the vehicle is traveling, the total weight of the driver and the motorcycle includes a suspension unit on the front side of the vehicle body attached to a front fork extending downward from the steering shaft, and a suspension unit on the rear side of the vehicle body provided between the swing arm and the cross member. Therefore, a large load is also applied to the cross member that supports the rear suspension unit. Therefore, it is desirable that the main frame, the pivot frame, and the cross member are more firmly connected to each other.

  Accordingly, an object of the present invention is to provide a motorcycle frame in which a main frame, a pivot frame, and a cross member are more firmly connected to each other.

  The present invention has been made in view of the above-described circumstances, and a motorcycle frame according to the present invention includes a head pipe that pivotally supports a steering shaft, and left and right main frames that extend from the head pipe to the rear of the vehicle body. And a left and right pivot frame that is connected to the rear portion of the main frame and extends downward from the connection portion, and a cross member that extends in the left and right direction and connects between the upper portions of the left and right pivot frames. Is provided with a suspension bracket for attaching a suspension unit that supports a rear wheel via a swing arm, and the cross member and the suspension bracket are integrally formed, and the cross member includes the main frame and A cross mechanism connected to the connecting portion between the pivot frames. It has a bus connection. By adopting such a configuration, the left and right connecting portions of the cross member are connected to both frames so as to cover the joint portion between the main frame and the pivot frame, thereby improving the joint strength between the main frame and the pivot frame. You can plan.

  The cross member connecting portion includes a front connecting portion extending forward along the main frame and connected to the main frame, and a lower connecting portion connected to the pivot frame and extending downward along the pivot frame. A side connection portion may be provided. With such a configuration, the joint strength between the main frame and the pivot frame can be further improved, and the connection between the cross member and the main frame and the pivot frame can be strengthened.

  Further, the cross member connecting portion may be connected to support an upper portion and a side portion of a connecting portion between the main frame and the pivot frame. With such a configuration, the connection between the main frame and the pivot frame, and the connection between the main frame and the pivot frame and the cross member can be further strengthened.

  Further, on the upper part of the left and right pivot frames, concave portions are formed in the wall portions on the opposite sides, and the cross member connecting portion covers the concave portion of the pivot frame and covers the pivot frame. It may be connected. With such a configuration, it is possible to reduce the weight of the pivot frame while strengthening the connection between the frames and the connection between the frames and the cross member.

  One of the rear end of the main frame and the upper end of the pivot frame has a bifurcated shape that opens up and down, and the other end has a shape that matches the shape of the one end. Then, the one end and the other end may be connected, and a cross member connecting portion of the cross member may be connected to the connecting portion. By adopting such a configuration, the main frame and the pivot frame are firmly connected so as not to be displaced in the vertical direction, and a long weld length can be secured.

  According to the motorcycle frame of the present invention, it is possible to provide a motorcycle frame in which the main frame, the pivot frame, and the cross member are more firmly connected to each other.

  Hereinafter, a motorcycle frame according to an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a side view of a motorcycle 1 of a motocrosser type, and FIG. 2 is a side view of a frame 2 provided in the motorcycle 1 shown in FIG. In FIG. 1, the frame 2 is indicated by a solid line, and the other portions are indicated by two-dot chain lines. In addition, the concept of direction used in the following description will be described as being the same as the concept of direction viewed from a rider (not shown) riding on the motorcycle 1.

  As shown in FIG. 1, the motorcycle 1 includes a front fork 3 having a predetermined caster angle and extending in a substantially vertical direction, and a front wheel 4 as a steering wheel is rotatably provided at a lower portion of the front fork 3. It is supported. A lower part of a steering shaft 6 extending in the vertical direction is connected to the upper part of the front fork 3, and a bar-type steering handle 7 extending in the horizontal direction is supported on the upper part of the steering shaft 6 at a central portion. Yes. The steering shaft 6 is pivotally supported by a head pipe 10 constituting the frame 2 so that the rider can turn the front wheel 4 left and right by turning the steering handle 7 left and right. Yes.

  As shown in FIGS. 1 and 2, the frame 2 includes a head pipe 10, and a main frame 11 that extends backward from the upper part of the head pipe 10 while facing slightly downward. The main frame 11 includes a pair of left and right main frames 111 and 112, and only the left main frame 111 is shown in FIG. The right main frame 112 is shown in FIG. Further, an upper portion of a down tube 12 extending downward while being slightly rearward is connected from the lower portion of the head pipe 10, and a lower frame 13 extends from the lower portion of the down tube 12. The lower frame 13 has a bifurcated shape that opens to the left and right, extends substantially downward from the lower portion of the down tube 12, curves in the middle, and extends rearward.

  The rear part of the lower frame 13 and the rear part of the main frame 11 are connected by a pivot frame 14. The pivot frame 14 is composed of a pair of left and right pivot frames 141 and 142, and the left pivot frame 141 connects the rear part of the left main frame 111 and the left rear part of the lower frame 13 to the right side. The pivot frame 142 connects the rear part of the right main frame 112 and the right rear part of the lower frame 13. 1 and 2, only the left pivot frame 141 is shown, and the right pivot frame 142 is shown in FIG. 6 described later.

  As shown in FIG. 2, a main frame tongue 10 </ b> A extends substantially rearward from the upper portion of the head pipe 10, and supports the front portion of the main frame 11 from above. Further, from the lower part of the head pipe 10, a tongue piece 10B for the down tube is extended substantially downward and supported so as to cover the upper part of the down tube 12 from the front.

  As shown in FIG. 2, a pivot hole 14A is formed at a position slightly lower than the center position in the vertical direction of the left pivot frame 141, and the front portion of the swing arm 16 extending substantially in the front-rear direction is the pivot hole 14A. Is pivotally supported by a pivot shaft 14 </ b> B inserted through the shaft. As shown in FIG. 1, a rear wheel 5 as a driving wheel is rotatably supported at the rear part of the swing arm 16, and the rear wheel 5 is swingable in the vertical direction about a pivot shaft 14B. It has become.

  As shown in FIG. 2, a suspension unit 17 is interposed between the upper part of the pivot frame 14 and the swing arm 16. The upper part of the suspension unit 17 is supported by a cross member 30 (described later) provided between the left and right pivot frames 141 and 142 via a suspension bracket 31 so as to be swingable.

  As shown in FIGS. 1 and 2, a gusset 20 and a support bar 21 for improving the rigidity of the frame 2 are provided between the front portion of the main frame 11 and the upper portion of the down tube 12. An engine E is mounted in a space S surrounded by the head pipe 10, the main frame 11, the down tube 12, the lower frame 13, and the pivot frame 14 constituting the frame 2. The engine E is a four-cycle engine in the present embodiment, and is supported on each part of the frame 2 by a plurality of engine mounting brackets 22, 22,... (See FIG. 2). As shown in FIG. 1, the output shaft (not shown) of the engine E is connected to the rear wheel 5 via a chain (or belt) C, and when the engine E is driven, the rear wheel 5 rotates in conjunction, The motorcycle 1 obtains a driving force.

  As shown in FIG. 1, a fuel tank 23 is provided above the main frame 11 and behind the steering shaft 6, and a seat 24 straddling the rider is disposed behind the fuel tank 23. ing.

  3 is a plan view of the cross member 30, FIG. 4 is a side view of the cross member 30, and FIG. 5 is a rear view of the cross member 30. FIG. 6 is a perspective view showing a connection form among the main frame 11, the pivot frame 14, and the cross member 30. Hereinafter, the configuration of the cross member 30 and the connection form among the main frame 11, the pivot frame 14, and the cross member 30 will be described in detail with reference to FIGS.

  As shown in FIG. 3, the cross member 30 is mainly composed of a cross portion 32 extending left and right and cross member connecting portions 33 provided at both ends thereof, and is integrally formed by casting. As shown by the broken line in the side view of FIG. 4, the cross portion 32 has a hollow cylindrical shape, and a rear side wall portion that has a normal line facing the front-rear direction and a substantially vertical wall surface at the outer peripheral rear portion. 32A is formed, and an upper side wall portion 32B is formed on the outer peripheral upper portion, which has a normal line facing substantially in the vertical direction and forms a substantially horizontal wall surface. The rear side wall portion 32 </ b> A and the upper side wall portion 32 </ b> B are formed over substantially the entire length of the cross portion 32. Further, as will be described later, the upper connection surface 38 (see FIG. 4) of the cross member connecting portion 33 extending downward from the left and right end portions of the cross portion 32 communicates with the internal space of the cross portion 32 and the inside A hole 38A is formed for removing the core sand packed in the space. As shown in FIG. 4, the cross section 32 may have a hollow cylindrical shape whose peripheral portion is substantially closed, or a hollow cylindrical shape whose lower portion is released. As an alternative configuration, the rigidity may be improved.

  As shown in FIG. 3, a pair of left and right suspension brackets 31 for pivotally supporting the upper portion of the suspension unit 17 (see FIG. 2), which is the center position in the left-right direction in the cross portion 32 and from the rear side wall portion 32A. It protrudes toward the rear (see also FIG. 4). The left and right suspension brackets 31 are provided in parallel at a predetermined interval, and through holes 31A for inserting support pins (not shown) are formed in the rear portions of the suspension brackets 31 so that their center axes coincide with each other. Yes.

  A pair of left and right rail brackets 34 for supporting a seat rail (not shown) is directed upward from the front side of the suspension bracket 31, that is, the center position in the left-right direction of the cross portion 32. It protrudes (see also FIG. 4). The left and right rail brackets 34 are provided in parallel with the same spacing as the left and right suspension brackets 31. A through hole 34A for inserting a support pin (not shown) is formed in the upper part of each rail bracket 34 so that the center axes thereof coincide with each other.

  Both the suspension bracket 31 and the rail bracket 34 are integrally formed with the cross member 30 by casting. Therefore, compared with the case where each bracket 31 and 34 and the cross member 30 are manufactured separately and welded, the connection strength can be improved and the dimensional accuracy can be improved. However, one or more of the cross member 30, the suspension bracket 31, and the rail bracket 34 are not necessarily formed by casting (die casting or the like), and may be formed by forging or pressing, for example. .

  As shown in FIG. 5, cross member connecting portions 33 extend downward from the left and right ends of the cross portion 32. When the left and right cross member connecting portions 33 are viewed from the back, the distance between the two is extended slightly toward the bottom, and the connecting portion between the cross portion 32 and the cross member connecting portion 33 is It has a smooth arc shape. As shown in FIG. 4, an extending portion 36 is formed in the lower portion of the cross member connecting portion 33 so as to extend from the obliquely upward front to the obliquely downward rear (see also FIG. 3). As shown in FIG. 3, when viewed in plan, the outer shape of the cross member 30 extending from the end of the cross portion 32 to each of the front portion and the rear portion of the extending portion 36 is an arc shape, As shown in FIG. 4, when viewed from the side, the outer shape of the portion from the upper portion of the cross member connecting portion 33 to the front portion and the rear portion of the extending portion 36 is also an arc shape. Thus, since the connection part between each part is comprised by the circular-arc-shaped external shape, the load added to the cross part 32 is efficiently transmitted to the extension part 36 which the cross member connection part 33 has.

  The extending portion 36 constitutes a substantially vertical surface and extends along the longitudinal direction of the extending portion 36, and extends and extends outward from the upper portion of the inner connecting surface 37 in the left-right direction. And an upper connection surface 38 extending along the longitudinal direction of the portion 36. In other words, the configurations of the inner connection surface 37 and the upper connection surface 38 are as follows. As shown in FIG. 6, the inner connection surface 37 is a connection portion (hereinafter referred to as “frame connection portion”) 26 of the main frame 11 and the pivot frame 14. In the vicinity thereof, the main frame 11 extends along the rear inner surface of the main frame 11 and the upper inner surface of the pivot frame 14 and along the longitudinal direction of the frames 11 and 14. Further, the upper connection surface 38 extends along the rear upper surface of the main frame 11 and the upper upper surface of the pivot frame 14 at and near the frame connection portion 26 of the main frame 11 and the pivot frame 14, and the frames 11, 14. It extends along the longitudinal direction. As shown in FIG. 4, a hole 38 </ b> A is formed at a substantially central position in the longitudinal direction of the upper connection surface 38 for removing core sand packed in the cross portion 32 during casting.

  In such a cross member 30, the portion extending in the obliquely upward direction and the portion extending in the obliquely downward direction in the extending portion 36 of the cross member connecting portion 33 constitute a front connecting portion 33A and a lower connecting portion 33B, respectively. . As shown in FIG. 6, the front connection portion 33A is mainly connected to the main frame 11, the lower connection portion 33B is mainly connected to the pivot frame 14, and the front connection portion 33A and the lower connection portion 33B. The portion between the two is connected to the frame connecting portion 26 of the main frame 11 and the pivot frame 14.

  On the other hand, as shown in FIG. 6, the upper end portion 14E of the pivot frame 14 has a bifurcated shape that opens up and down in a side view, and the rear end portion 11E of the main frame 11 is connected to the upper end portion 14E of the pivot frame 14. The shape matches the shape. In other words, the rear end portion 11E of the main frame 11 has a substantially trapezoidal shape with the upper and lower portions partially cut away. The upper end portion 14E of the pivot frame 14 is cut out into a substantially trapezoidal shape so that the upper end portion of the upper end portion 14E matches the shape of the rear end portion 11E of the main frame 11, and the upper and lower portions are sharpened. 14F and 14G are formed, and it has a bifurcated shape in which an end surface 14H perpendicular to the longitudinal direction of the pivot frame 14 is formed at the center portion in the vertical direction. Then, the rear end portion 11E of the main frame 11 and the upper end portion 14E of the pivot frame 14 are abutted and welded along the abutting portion, whereby the main frame 11 and the pivot frame 14 have a long welding length. It is connected. Thus, since the main frame 11 and the pivot frame 14 have a long weld length, the connection strength between the frames 11 and 14 is improved. Further, in the upper inner part of the pivot frame 14, that is, the wall parts on the opposite sides of the left and right pivot frames 141, 142 are formed recesses 14C for thinning, and a large number of recesses 14C are formed in the recesses 14C. Ribs 14D are provided.

  The cross member 30 described above is installed between the left and right frame connecting portions 26 of the main frame 11 and the pivot frame 14. That is, as shown in FIG. 6, the cross member 30 is disposed between the left and right frame connection portions 26 from above, with the longitudinal direction of the cross portion 32 directed in the left-right direction. The left and right inner connection surfaces 37 of the cross member connecting portion 33 abut against the left and right frame connecting portions 26 between the frames 11 and 14 from the center side in the left and right direction of the vehicle body, and the cross member connecting portion 33 has. The left and right upper connection surfaces 38 are in contact with the frame connection portion 26 from above.

  As a result, the inner connection surface 37 and the upper connection surface 38 of the cross member connection portion 33 are in the frame connection portion 26 between the frames 11 and 14, the rear end portion 11 </ b> E of the main frame 11, and the upper end portion 14 </ b> E of the pivot frame 14. , Covering the inside and top of each. In this state, the cross member 30 is welded along the outer edge of the inner connecting surface 37 and the outer edge of the upper connecting surface 38 in the cross member connecting portion 33, and the cross member 30, the main frame 11, and the pivot frame 14 support each other. In this state, it is firmly connected.

  Further, the recess 14C formed in the upper portion of the pivot frame 14 and the cross member connecting portion 33 of the cross member 30 covering the recess 14C form an intermediate structure having an internal space, and a certain strength is ensured. Yes. Therefore, the rib 14D is not necessarily required in the concave portion 14C of the portion covered with the cross member connecting portion 33. Although not shown in the present embodiment, the rib 14D is not provided in this portion.

  Further, in the main frame 11 and the pivot frame 14, a recess 40 is formed in a portion where the cross member connecting portion 33 of the cross member 30 abuts slightly compared with the vicinity of the outside of the portion. Therefore, when the cross member 30 is disposed between the frames 11 and 14, the cross member 30 can be easily positioned with respect to the main frame 11 and the pivot frame 14 by fitting the cross member connecting portion 33 into the recess 40.

  According to the frame 2 having such a configuration, the cross member 30, the main frame 11, and the pivot frame 14 are firmly connected to each other, and a load applied to the cross member 30 via the suspension bracket 31 is applied to the cross member 30. The members 30 can be efficiently transmitted to the main frame 11 and the pivot frame 14 from the extended portion 36 of the cross member connecting portion 33 of the member 30 and dispersed.

  Note that the frame according to the present invention can be applied not only to the motocrosser described in the present embodiment, but also to an American type or a road racer type motorcycle.

  The present invention can be applied to motorcycles of a motocrosser type, an American type, and a road racer type, and can be employed in these body frames.

1 is a side view of a motocrosser type motorcycle employing a frame according to an embodiment of the present invention. Fig. 2 is a side view of a frame provided in the motorcycle shown in Fig. 1. It is a top view of the cross member shown in FIG. FIG. 4 is a side view of the cross member shown in FIG. 3. FIG. 4 is a rear view of the cross member shown in FIG. 3. It is a perspective view which shows the connection form between the main frame shown in FIG. 2, a pivot frame, and a cross member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Frame 6 Steering shaft 10 Head pipe 11, 111, 112 Main frame 14, 141, 142 Pivot frame 14C Recessed part 16 Swing arm 17 Suspension unit 26 Frame connection part 30 Cross member 31 Suspension bracket 33 Cross member connection part 33A Front side Connection part 33B Lower connection part

Claims (4)

A head pipe that pivotally supports the steering shaft, left and right main frames that extend from the head pipe to the rear of the vehicle body, left and right pivot frames that are connected to the rear portion of the main frame and extend downward from the connecting portion, and to the left and right A cross member that extends and connects between the upper parts of the left and right pivot frames;
The cross member is provided with a suspension bracket for attaching a suspension unit that supports a rear wheel via a swing arm, and the cross member and the suspension bracket are integrally formed,
The cross member has a cross member connection portion connected to a connection portion between the main frame and the pivot frame,
In the upper part of the left and right pivot frames, there are formed recesses in the wall portions facing each other, and the cross member connecting portion covers the recess of the pivot frame and is connected to the pivot frame. A motorcycle frame characterized by that.   The cross member connection portion includes a front connection portion extending forward along the main frame and connected to the main frame, and a lower connection extending downward along the pivot frame and connected to the pivot frame. The motorcycle frame according to claim 1, wherein a frame is provided.   3. The motorcycle frame according to claim 1, wherein the cross member connecting portion supports and connects an upper portion and a side portion of a connecting portion between the main frame and the pivot frame.   One of the rear end of the main frame and the upper end of the pivot frame has a bifurcated shape that opens up and down, and the other end has a shape that matches the shape of the one end. 4. The cross member connecting portion of the cross member is connected to the one end portion and the other end portion, and a cross member connecting portion of the cross member is connected to the connecting portion. Motorcycle frame.

Images