JPH0319114B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a frame structure for a straddle-type vehicle including a motorcycle, a three-wheeled vehicle, and the like.

Background Art The frame structure shown in Fig. 10 is, for example,
This is disclosed in Japanese Patent No. 17768, and as shown in the figure, it has a pair of left and right main pipes 102 connected at their front ends to a head pipe 101 that supports a front fork. Main pipe 102
is a swing arm 104 that pivotally supports the rear wheel 103.
A pivot part 105 for pivotally supporting the front end of the pivot part 105 is provided at the rear end, and is integrally formed over the entire length.

The above frame structure includes a head pipe 101,
It is assembled by joining the main pipe 102 and other members such as stays to each other by welding, but it is difficult to completely prevent the generation of residual stress due to welding, and the so-called caster angle and Errors due to distortion may occur in the center-to-center distance between the center of the head pipe 101 and the pivot portion 105, which is an element of frame rigidity. In this case, after the assembly of the frame structure is completed, it is necessary to use special equipment to remove distortion from the frame structure as a whole, and such distortion removal work requires a long time and skill, leading to an increase in frame manufacturing costs. .

By the way, in the conventional frame structure described above, considering that the engine 106 is not only supported by the down tube 107 but also suspended by the main pipe 102, it is possible to increase the rigidity of the main pipe 102. There is a need. To achieve this, for example, the distance between the left and right main pipes 102 may be increased, or the cross-sectional dimensions of the main pipes themselves may be increased. There is a disadvantage that a good riding feeling cannot be obtained.

Summary of the Invention [Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to contribute to facilitating the management of frame structure accuracy, and to provide a frame with desired rigidity. Moreover, it is an object of the present invention to provide a frame structure that allows a driver a large degree of freedom in riding posture.

[Configuration of the Invention] The frame structure for a straddle type vehicle according to the present invention has the following features:
a pair of left and right first frame members that are coupled at their front ends to a head pipe that rotatably supports a front fork and extend rearward and downward;
a pair of left and right second frame members that are joined to the rear end of the frame member and extend downward, and have a pivot portion that pivotally supports the front end of a swing arm that pivotally supports the rear wheel; The engine is supported by the member, the distance between each of the pivot parts in the left-right direction of the vehicle is made smaller than the distance between the engine support parts of each of the first frame members, and a step holder is disposed near the pivot part. It is characterized by what it did.

[Operation of the Invention] In the frame structure having such a configuration, manufacturing errors due to distortion that occur when assembling the frame by welding are adjusted when joining the second frame member to the first frame member, and in addition The width around the step holder is narrowed, and the width of the pair of left and right first frame members, which are the engine support parts, is ensured to be sufficiently large.

Embodiments Hereinafter, a motorcycle including a frame structure as an embodiment of the present invention will be described with reference to the accompanying drawings.

Figure 1 shows an aluminum double cradle type frame structure 1 as a first embodiment of the present invention.
It shows a motorcycle equipped with

As shown in the figure, a fairing member 2 and a rear cowl member 3 are provided at the front and rear parts of the motorcycle.
is provided, and the rear cowl member 3 is attached to the seat 4.
and the lower part of the fuel tank 5. These fairing member 2, rear cowl member 3, seat 4, and fuel tank 5 are supported by the frame structure 1 together with an engine 6 disposed at the lower center of the motorcycle.

A head pipe 8 made of aluminum alloy or steel is provided at the front of the frame structure 1, and includes a steering mechanism 9 and a front fork 10.
is connected to the front wheel 11 via
Further, the rear portion of the frame structure 1 is connected to a rear wheel 12 via a swing arm, which will be described later.

As is clear from FIGS. 2 to 4, the frame structure 1 uses members formed into square pipe shapes by extrusion and pultrusion, and is assembled by welding them together. The head pipe 8 is mounted with its upper and lower parts supported by the front ends of the left and right main pipes A15 (portions indicated by dimension Ma in FIG. 2) as a pair of first frame members and the same pair of sub-main pipes 16. It is being A rear end portion of the sub-main pipe 16 is connected to a substantially intermediate portion of the main pipe 15. These head pipe 8, main pipe A15, and sub-main pipe 16 are assembled in advance as a first block, and the machining of head pipe 8 is performed when the assembly of the first block is completed. As described above, the main pipe A15 serving as the first frame member is connected to the head pipe 8 at its front end and extends rearward and downward.

A pair of left and right down tubes A17 whose upper ends are fixed to the head pipe 8 and the main pipe A15, respectively, extend from the vicinity of the front end of the main pipe A15.
(The part indicated by the dimension Da in FIG. 2) extends diagonally downward.

Further, an engine hanger 17c for supporting the engine 6 is fixed to both the left and right down tubes A17 and near their lower ends. The left and right down tubes A17 are assembled in advance as a second block together with the down tube upper cross pipe 17d, the down tube lower cross pipe 17e, etc. interposed between the two down tubes.

A pair of left and right down tubes B20 (dimensions shown in FIG.
The part indicated by Db) is the down tube A1
Together with 7, it constitutes the entire down tube, which is the lower part of the entire frame structure (however,
Only the left side of the mating portion 18 and inner pipe 19 are shown). Note that the joining portion 18 makes the entire down tube discontinuous and divides it into a down tube A17 and a down tube B20.

Down tube A17 and down tube B20
The portion where the matching portion 18 is provided is formed in a straight line, although it is a short section. In this way, since the mating portion 18 is provided on a straight portion, it is easier to use than when the mating portion is provided on a curved portion where complex moments such as bending moments, torsional moments, or complex moments of these are often applied. This makes it easier to increase the strength of the frame structure as a whole. Further, the joining portion 18 is provided obliquely with respect to the extending direction of both down tubes A17 and B20, and the welding length at the joining portion is relatively large. The inner pipe 19 is fitted into the down tubes A17 and B20 and then fixed to the down tubes by, for example, plug welding, and serves to reinforce the joint portion 18. Furthermore, plug welding of the inner pipe is performed prior to butt welding of the mating portion 18.

A pair of left and right gussets 20d made of aluminum alloy or steel are welded to the front surfaces of the left and right down tubes B20, and are formed with a pivot portion 20c for pivotally supporting the front end of the swing arm 21 that pivotally supports the rear wheel 12. ing. In addition, a step holder 2 is provided on the rear surface of both down tubes B20.
2 (see Figure 1) stay 23 for attaching
is fixed.

Near the upper end of the down tube B20, a first
The main pipe B25 (portion indicated by dimension Mb in FIG. 2), which constitutes the entire main pipe that is the upper part of the entire frame structure together with the main pipe A15 as a frame member and is aligned in a straight line with the main pipe A15, is at the rear end. All ends of the main pipe B25 are fixed to the rear end of the main pipe A15 at mating portions 26, for example, by butt welding. Gusset 20d is this main pipe B2
5 and is also welded to the main pipe B. Incidentally, the joining portion 26 makes the entire main pipe discontinuous and divides it into a main pipe A15 and a main pipe B25.

By the way, in the explanation so far, the main pipe A15 has been referred to as the first frame member, but on the other hand, the main pipe B25 mentioned above has been referred to as the first frame member.
and a gusset 20d having a pivot portion 20c.
and gusset 20d of down tube B20.
The combined body with the joined portion (the portion indicated by the dimension Dα in FIG. 2) is collectively referred to as the second frame member. That is, the second frame member has a pivot portion 20c that pivotally supports the swing arm 21, and the main pipe A15 that is the first frame member.
Its front end joins to the rear end, and the whole body lengthens downward.

As shown in FIGS. 2 and 3, an engine hanger 15a is disposed at a connecting portion between the main pipe A15 and the main pipe B25, that is, at a portion where a mating portion 26 is provided. The engine hanger 15a is welded to both the main pipes A15 and B25, and by providing the engine hanger at this position, the connection between the two main pipes A15 and B25 at the joint portion 26 is reinforced. Note that welding between the engine hanger 15a and the main pipes A15 and B25 is performed prior to butt welding of the joint portion 26.

The main pipe B25, which constitutes a part of the second frame member described above, is bent toward the inside of the vehicle body in front of the seat 4, and is bent toward the rear of the vehicle body at the rear of the bent portion. A knee grip portion 80 is formed. Moreover, because of this configuration, the distance in the left-right direction of the vehicle between the pair of left and right pivot portions 20c (only the left side is shown in the figure) is greater than the distance between each of the pair of left and right main pipes A15 as the first frame member. The distance between the engine hangers 15a provided as engine support parts is smaller than the distance between the engine hangers 15a. That is, the width dimension around the step holder 22 mentioned above is smaller than the distance between the engine support parts of the left and right main pipes A15.

As mentioned above, since the width around the step holder located at the bottom of the vehicle body is smaller than the distance between the engine support parts of the main pipe A15, the vehicle body can be slimmed down and the driver can enjoy more freedom in riding posture. This increases the steering angle and provides a good riding feeling, as well as improving maneuverability of the vehicle body and increasing the bank angle. Furthermore, regarding the pair of left and right main pipes A15, which act as engine support parts without being involved in the ride feeling, the separation distance and cross-sectional dimensions of these can be increased, ensuring the desired rigidity for engine support. It will be done.

On the other hand, the front ends of a pair of left and right seat rails 28 for supporting the seat 4 are fixed to the front ends of both the left and right main pipes B25, and the seat rails extend diagonally rearward. An upper end portion of a down tube B20 is fixed and reinforced by a gusset 28a to approximately the middle portion of the seat rail 28. Further, a cross pipe 29 is horizontally suspended between the respective rear end portions of the left and right seat rails 28. Further, a seat tube 30 is wound around the intermediate portion of the seat rail 28.

Above down tube 20, main pipe B25
The seat rail 28 and the like are assembled in advance as a third block.

As described above, the main pipe A15, the sub-main pipe 16, the down tube A17, the down tube B20, the main pipe A25, and the seat rail 28 preferably have a rectangular or square cross section perpendicular to their extending direction. It is formed.

When assembling the entire frame structure 1, the first to third blocks may be finally welded together at the mating portions 18 and 26. In this way, by welding the joining parts 18 and 26 at the final stage of the frame structure assembly work,
It is possible to adjust manufacturing errors due to distortions that occur when assembling the frame structure by welding, especially the caster angle shown by θ in the figure, and the center of the front fork rotation center and the pivot part 20c shown by L. Distances etc. are determined accurately.

The method of welding the joints 18 and 26 may be as shown in FIGS. 5a and 5b.

The welding method shown in FIG. For example, butt welding is performed along the cutting line perpendicular to the extending direction of both main tubes.

In addition, in the welding method shown in FIG. 5b, no inner pipe is provided and the down tube A
17 and B20 (or main pipes A15 and B25) are inclined with respect to the extending direction of both down tubes (or main pipes),
A reinforcing plate 32 made of the same material is interposed between both cuts, and fillet welding, for example, is performed on the reinforcing plate.

6 and 7a and 7b show an aluminum double cradle type frame structure 34, which is a second embodiment of the present invention.

In this embodiment, a head pipe 35 rotatably supports a front fork (not shown).
, a main pipe 36 (portion indicated by dimension Mc in FIG. 6) and a sub-main pipe 37 as a pair of left and right first frame members supporting the upper and lower parts of the head pipe 35, respectively, and the left and right main pipes 36. A stay 38 which is interposed between the two and whose both ends are welded to the main pipe 36 together with the sub-main pipe 37, and a stay 39 which is provided between the head pipe 35 and the sub-main pipe 37.
etc., before assembling the entire frame structure.
It is produced as a block. Note that the main pipe 36 forms the upper part of the entire frame structure. The stay 38 has a pair of left and right engine hangers 36a.
is provided, and the main pipe 36 supports an engine (not shown) via this stay 38. Further, the machining of the head pipe 35 is performed when the assembly of the first block is completed. As described above, the main pipe 36 serving as the first frame member is connected to the head pipe 35 at its front end and extends rearward and downward.

A pair of left and right down tubes A40 whose upper ends are welded near the front end of the sub-main pipe 37
(The portion indicated by dimension Dc in FIG. 6) extends obliquely downward. However, this down tube A40 is not connected to the stay 39.
Further, both down tubes A are also provided with engine hangers. Left and right down tube A4
0 is prefabricated as a second block together with a cross stay 41 (shown in FIG. 7b) interposed between both down tubes A.

A pair of left and right down tubes B44 (dimensions shown in FIG.
The part indicated by Dd) is the down tube A4
Together with 0, it constitutes the entire down tube without forming the lower part of the frame structure as a whole (however,
Only the left side of the mating portion 42 and inner pipe 43 are shown). The joining portion 42 divides the entire down tube into a down tube A40 and a down tube B44.

Further, the down tubes A40 and B44 are formed in a straight line at the portion where the mating portion 42 is provided. The joining portion 42 is inclined with respect to the direction of extension of both down tubes A40 and B44, and the welding length at the joining portion is relatively large. Further, the inner pipe 43 is connected to both down tubes A40 and B44 by plug welding. Further, plug welding of the inner pipe is performed prior to butt welding of the mating portion 42. A gusset 44b in which a pivot portion 44a is formed for pivotally supporting the front end of a swing arm (not shown) that pivotally supports a rear wheel (not shown) is welded to the front surface of the left and right down tubes B44. There is. Further, a stay 45 for attaching a step holder (not shown) is fixed to the rear surface of the down tube B44.

The left and right down tubes B44 are manufactured in advance as a third block together with a stay 46 interposed between the two down tubes B.

The upper end of the down tube B44 is the mating part 49
It is fixed to the rear end of the main pipe 36 as the first frame member by butt welding. The stay 38 is also welded to the upper end of the down tube B44 around the joint portion,
By doing this, the state of connection between the main pipe 36 and the down tube B44 at the joint portion 49 is strengthened. Note that welding of the stay 38 and down tube B44 is performed prior to butt welding of the mating portion 49.

By the way, in the explanation so far, the main pipe 36 has been referred to as the first frame member, but on the other hand, the down tube B44 described above has been referred to as the first frame member.
gusset 44 including the upper half portion (the portion indicated by dimension DB in Fig. 6) and the pivot portion 44a.
The combined body with b is collectively referred to as a second frame member.
That is, this second frame member has a pivot portion 44a that pivotally supports a swing arm (not shown),
Its front end is connected to the rear end of the main pipe 36, which is the first frame member, and extends downward as a whole.

As shown in FIG. 7b, the left and right down tubes A40 are bent so as to approach each other as they go downward, and the left and right down tubes A40 are bent to approach each other downward.
The distance between the pivot portions 44a of the frame members in the left-right direction of the vehicle is narrow and approximately equal to the width between the lower ends of both down tubes A40. Therefore, the distance between the pair of left and right pivots 44a (only the left one is shown in the figure) in the left and right direction of the vehicle, and the distance between the pair of left and right pivots 44a (only the left one is shown in the figure), and the distance between the pair of left and right pivots 44a, which are fixed as engine support parts, to each of the pair of left and right main pipes 36 as the first frame member are determined. two engine hangers 3
It is smaller than the distance between 6a. In other words, the width around the step holder described above is smaller than the distance between the engine support parts of the left and right main pipes 36.

As mentioned above, since the width around the step holder located at the bottom of the vehicle body is smaller than the distance between the engine support parts of the main pipe 36, the vehicle body can be slimmed down and the driver can enjoy more freedom in riding posture. This increases the steering angle and provides a good riding feeling, as well as improving maneuverability of the vehicle body and increasing the bank angle. Furthermore, as for the pair of left and right main pipes 36, which act as engine support parts without being involved in the riding feeling, the separation distance and cross-sectional dimensions can be increased, so that the desired rigidity for supporting the engine can be ensured. It will be done.

On the other hand, the front end of the seat rail 50 is fixed to the upper end of both the left and right down tubes B44,
The seat rail extends diagonally rearward. Approximately middle part of seat rail 50 and down tube B44
There is a rear stay 51 and a sub-rear stay 5 between
2 is provided.

As is particularly clear in Figure 7a, there is a stay 5 between the left and right seat rails 50 and the rear stay 51.
3a and 53b are placed horizontally. Further, a cross pipe 54 is provided between each rear end portion of both seat rails 50.
is suspended horizontally.

The seat rail 50, rear stay 51, and sub-rear stay 52 are assembled in advance as a fourth block.

When assembling the entire frame structure 34,
The first to fourth blocks are sequentially welded, and finally the mating parts 42 and 49 are welded.
By welding the joining parts 42 and 49 at the final stage of the frame structure assembly work in this way, it is possible to absorb manufacturing errors caused by distortions that occur when assembling the frame structure by welding, especially as shown by θ in the figure. The caster angle and the center-to-center distance between the center of rotation of the front fork and the pivot portion 44a, indicated by L, are precisely dimensioned.

Incidentally, the method of welding the joining portions 42 and 49 may include various other embodiments, similar to the first embodiment described above.

FIG. 8 shows a motorcycle equipped with an aluminum frame structure 57 as a third embodiment of the present invention. The motorcycle is of the same type as the motorcycle equipped with the first embodiment.

As shown in FIGS. 9a and 9b, in this embodiment, the overall shape of the frame structure is
It is formed similarly to the embodiment.

In this embodiment, the down tube B20 and the main pipe B25 are cut out by a predetermined amount, and in their place, a connecting member 59 made of die-cast aluminum and integrally formed with the step holder 58 is inserted. . A groove 59a into which the down tube B20 and the main pipe B25 can be fitted is formed in the connecting member, and the down tube B20 and the main pipe B25 are welded to the connecting member 59 after being fitted into the groove 59a. There is.

Further, in the upper part of the connecting member 59, a support hole 5 for pivotally supporting a rear suspension shock absorber is provided.
9b is formed. Further, 59c is a main step.

As shown in FIGS. 8 and 9a, the connecting member 5
9 includes a pivot portion 59 for pivotally supporting the front end portion of the swing arm 21 that pivotally supports the rear wheel 12.
e is formed.

Here, the step holder 5 of the connecting member 59
8 and the main pipe B25 connected to the connecting member 59 are collectively referred to as the second frame member. On the other hand, the main pipe A15 to which the main pipe B25, which is the first half of the second frame member, is joined at its front end is referred to as a first frame member. That is, the second frame member has a pivot portion 59e for pivotally supporting the swing arm 21, and extends downward as a whole. Note that an engine hanger (not shown) that supports the engine 6 is welded to the main pipe A15, which is the first frame member.

The main pipe B25, which constitutes a part of the second frame member described above, is bent toward the inside of the vehicle body in front of the seat 4, and is bent toward the rear of the vehicle body at the rear of the bent portion. A knee grip portion 80 is formed. Moreover, because of this configuration, the distance in the vehicle left-right direction of each of the pair of left and right pivot portions 59e (only the left side is shown in the figure) is smaller than that of each of the pair of left and right main pipes A15 as the first frame member. The distance is smaller than the distance between engine hangers (not shown) provided as engine support parts. That is, the width dimension around the step holder 58 described above is the same as that of the left and right main pipes A15.
This distance is smaller than the distance between the engine supports.

As mentioned above, since the width around the step holder located at the bottom of the vehicle body is smaller than the distance between the engine support parts of the main pipe A15, the vehicle body can be slimmed down and the driver can enjoy a free riding posture. This increases the steering angle and provides a good riding feeling, as well as improving maneuverability of the vehicle body and increasing the bank angle. Furthermore, regarding the pair of left and right main pipes A15, which act as engine support parts without being involved in the ride feeling, the separation distance and cross-sectional dimensions of these can be increased, ensuring the desired rigidity for engine support. It will be done.

FIG. 9c shows an example of the connection between the down tube B20 and the main pipe B25 and the connecting member 59 using bolts and nuts instead of welding. It is conceivable to combine the above two at least in one place depending on the above. In this example, if long holes are provided in the frame of the connecting portion, the technique of the present invention is unnecessary. It goes without saying that the technique of the present invention is required when the down tube B20 and main pipe B25 are further welded to the connecting member 59 in addition to the connection using the bolt members 60 and nuts 61. Although not shown, each tube to be welded to the connecting member 59 may have a length that allows direct welding.

As described above, the frame structure according to the present invention employs a method in which the frame structure is manufactured in several blocks divided by the above-mentioned joints and other parts before being assembled. Compared to the conventional method in which all parts are manufactured and managed separately, precision control of the frame structure and inventory control of parts are simplified.

Further, since the head pipe can be machined at the time of manufacturing the block portion, the object to be machined can be relatively small, making the machining process easy.

Effects of the Invention As detailed above, in the frame structure for a straddle type vehicle according to the present invention, the frame connecting the head pipe that supports the front fork and the pivot part that pivotally supports the swing arm is attached to the front end of the head pipe. a pair of left and right first frame members that are joined together at a point and extend rearward and downward;
a pair of left and right second frame members that are joined to the rear ends of the frame members and extend downward and have the pivot portions, the first frame members support the engine, and the pivot portions in the left-right direction of the vehicle The distance between each of the first frame members is smaller than the distance between the engine supporting parts of each first frame member, and a step holder is disposed near the pivot part.

In this way, since the joint part of the first and second frame members is configured to absorb the relative displacement between the head pipe and the pivot part, the manufacturing error due to distortion that occurs when assembling the frame structure by welding can be absorbed by the joint part. This makes it easy to control the accuracy of the frame structure because it can be adjusted when connecting the frames, and there is no need for long hours of strain relief work using special equipment after the assembly work is completed.

In addition, as mentioned above, since the width around the step holder located at the bottom of the vehicle is smaller than the distance between the engine support parts of the left and right first frame members, the unit can be slimmed down and the driver can This increases the degree of freedom in the riding position of the vehicle and provides a good riding feeling, as well as improving the maneuverability of the vehicle body and increasing the bank angle.
Since the pair of first frame members, which are engine support parts that are not involved in riding feeling, can have a large separation distance and a large cross-sectional dimension, desired rigidity can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a side view of a motorcycle equipped with a frame structure as a first embodiment of the present invention;
3 and 4 are a side view, a plan view, and a front view, respectively, of the frame structure shown in FIG. 1, and FIGS. An enlarged view showing a welding example, FIG. 6, FIG. 7 a and b are respectively a side view, a top view, a front view, and an eighth
The figure is a side view of a motorcycle equipped with a frame structure as a third embodiment of the present invention, FIGS. 9a and 9b.
is a partially enlarged view of the frame structure shown in FIG. 8, FIG. 9c is a view showing a modification of the frame structure shown in FIG. 8, and FIG. 10 is a side view of a motorcycle including a conventional frame structure. It is. Explanation of symbols of main parts, 1, 34, 57... Frame structure, 4... Seat, 5... Fuel tank,
6...engine, 8,35...het pipe, 1
5...Main pipe A, 16...Sub main pipe, 17,40...Down tube A, 18,2
6, 42, 49... Joining portion, 20, 44... Down tube B, 22, 58... Step holder, 25... Main pipe B, 28, 50... Seat rail, 29, 54... Cross pipe.

Claims (1)

[Claims] 1 A pair of left and right first frame members that are connected at their front ends to a head pipe that rotatably supports a front fork and extend rearward and downward; A pair of left and right second pivot portions extending toward the rear wheel and having a pivot portion pivotally supporting the front end portion of the swing arm pivotally supporting the rear wheel.
a frame member, the engine is supported by the first frame member, and the distance between each of the pivot portions in the left-right direction of the vehicle is smaller than the distance between the engine support portions of each of the first frame members; A frame structure for a straddle type vehicle, characterized in that a step holder is arranged near a pivot part.