JPH0811556B2 - Body frame for motorcycles - Google Patents

Description

Description: [Industrial application] The present invention relates to a casting frame obtained by die casting for a motorcycle, and particularly to a lightweight and high-strength frame.

[Prior Art] It is known that a motorcycle frame is cast and integrally molded using a light alloy such as aluminum.
There is also a body frame in which a pair of upper and lower ribs are formed on the side surface (see Japanese Patent Laid-Open No. 61-6084).

By integrally casting aluminum light alloy or the like as described above, the wall thickness can be freely set, so that a frame corresponding to the load distribution can be created.

Therefore, a sufficient intensity distribution can be achieved,
Further, by forming a part having a large surface area and a small thickness, an appropriate elasticity can be imparted.

Moreover, the ribs can improve the rigidity and reduce the weight.

[Problems to be Solved by the Invention] By the way, in the case of general casting in which aluminum is formed by a sand mold, the wall thickness is about 4 mm, which is the minimum, so that it becomes relatively heavy.

On the other hand, in die casting, it is generally said that the balance between moldability and strength is when the wall thickness is about 2.5 mm. If the wall thickness exceeds 4 mm, it becomes easier to rinse and it becomes difficult to increase the strength despite the increase in the wall thickness.

However, when the wall thickness is set to about 2.5 mm, it is necessary to further strengthen the structure in order to cover the thinning and achieve sufficient frame rigidity. For this reason, it is desired to realize a lightweight structure using die casting and to obtain a highly rigid structure with sufficient practicality.

In particular, since the rear swing arm support portion is provided with the pivot mounting portion and the rear cushion unit mounting portion for the front end portion of the rear swing arm, the stress concentration is large.

Therefore, in order to make the vehicle body as light as possible and to obtain sufficient rigidity, the rear swing arm support part should be lightweight and highly rigid, and the area around the pivot attachment part where stress is most concentrated should be efficient. It is desired to have high rigidity.

In Japanese Patent Laid-Open No. 61-178276, a pair of left and right split frames are separately manufactured by casting, and each split frame has a main frame part and a rear swing arm support part integrally molded, and a pivot mount. Radial ribs are shown around the part. However, since it is considered that each of the divided frames is formed into a substantially I-shaped cross section by the general casting, there is a limitation in the above-mentioned molding. It seems that the weight must be increased.

In addition, even if the thickness is reduced by die casting,
The main frame part is only provided with ribs that are substantially parallel to each other vertically, and this and the radial ribs around the pivot attachment part are not sufficient to obtain the required rigidity, so
Because the rigidity must be increased by the wall thickness, it must be made considerably thicker than the wall thickness that should be thinned by die casting, which is beyond the limits of general casting.
It is thought that the wall thickness must be set to a level not much different from that of the general casting, and as a result, the advantage of thinning by die casting cannot be fully enjoyed.

Further, in JP-A-62-26177, a main frame as a single member which is provided in the center of a vehicle body and is not divided into left and right is cast in a substantially I-shaped section, and upper and lower ribs and upper and lower ribs are formed on an outer surface thereof. And a vertical rib that connects the ribs of FIG. However, it seems that this main frame also has to be relatively heavy due to the rib structure and the restrictions on the molding. Moreover, the ribs are formed on the outer surface of the main frame, which is not preferable in appearance.

Further, Japanese Patent Application Laid-Open No. 61-291281 discloses the above-mentioned 62-2617.
A main frame having a shape similar to that described in No. 7 and having a channel-shaped cross section and ribs formed inside thereof is shown. However, this main frame also has the same problem in terms of wall thickness as before, and because the ribs are provided inside the channel-shaped member, it is not visible, but for the reasons of molding, the open side It is limited to parallel ribs extending to and cannot have a special structure.

Further, in Japanese Patent Laid-Open No. 59-77991, each part of the casting frame divided into front and rear is formed in a left and right half-divided state, and ribs are provided on each inner side, and these left and right half-divided parts are formed. It is shown as a hollow body that is put together at the top and bottom.

However, in this structure, the left and right halves have to be joined together at the lower part in order to increase the rigidity, so that the weight increases steadily due to the presence of this joined portion. In addition, if the lower part is deleted, it is considered that it is difficult to obtain the necessary rigidity with the disclosed rib structure even if the number is appropriately increased, and as a result, the overall weight is light. It seems that it is not suitable for manufacturing a large frame that is hard to be made and is large enough to integrally mold the main frame part and the rear swing arm support part as in the main subject.

It should be noted that the above-mentioned JP-A-59-77991 and JP-A-61-291281 each have a description suggesting the use of die casting. However, these merely refer to one specific means in the conventional cast molding, and do not suggest a specific divided frame structure and a rib structure as in the invention of the present application described later, so that the effect is as described above. It seems that the weight can be expected to be equivalent to or slightly less than that of general casting.

Therefore, an object of the present invention is to provide a vehicle body frame that realizes a sufficient weight reduction by utilizing die casting, and at the same time can achieve both practical use and high rigidity.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the motorcycle frame of the present invention comprises left and right divided frames extending rearward from the head pipe, and the left and right divided frames are respectively A head pipe support part, a main frame part for supporting an engine, etc., and a rear swing arm support part provided with a pivot mounting part for pivotally supporting the front end part of the rear swing arm, are integrally molded and reinforced. In a motorcycle body frame having ribs, the left and right divided frames are formed by die casting so that main frame portions have symmetrical substantially angular cross sections, and the left and right divided frames are assembled. Sometimes the body frame has a generally downward U-shaped cross section, and the ribs have the required strength over the entire inner surface of each divided frame. Accordingly, the rib density of the rear swing arm support portion is set to be the highest, and a large number of ribs are formed radially around the pivot attachment portion, and the ribs intersect a part of the radial ribs. Is provided in the vicinity of the pivot mounting portion, and further, the ribs are formed in a lattice shape over substantially the entire range of the main frame portion.

[Operation of the Invention] The motorcycle body frame cast by die casting of the present invention has a large number of ribs formed on the entire inner surface of each divided frame, and the distribution density thereof is made coarse and dense according to required strength, Of these, the rib density of the rear swing arm support was made the highest.

Further, a large number of ribs are formed radially around the pivot mounting portion, ribs that intersect a part of the radial ribs are provided in the vicinity of the pivot mounting portion, and the ribs of the main frame portion are arranged in a grid pattern over substantially the entire range. Crossed

Therefore, the rear swing arm support portion, which receives the largest load during traveling, has high rigidity. Moreover, the rigidity around the pivot mounting portion has a radial rib and a rib provided in the vicinity of the pivot mounting portion so as to intersect the radial rib,
With these intersections, the efficiency is improved.

On the other hand, the ribs of the portion other than the rear swing arm support portion are relatively rough, and the ribs of the main frame portion are intersected in a lattice pattern over almost the entire range. Will be improved efficiently.

In addition, the left and right divided frames can be formed as thin as possible by die-casting as much as the increased rigidity due to these structures, and each of the left and right divided frames is formed in a symmetrical substantially angular cross section. As a result, ribs can be easily formed on the inner side of each, and the ribs intersecting with each other can be formed.

Moreover, since the vehicle body frame at the time of assembling these left and right divided frames has a downward substantially U-shaped cross section, the entire weight can be further reduced by the amount corresponding to this open portion.

[Embodiment] FIGS. 1 to 5 show an embodiment of the present invention. In the motorcycle shown in FIG. 1, reference numeral 1 is a handlebar, 2 is a front fork, and 3 is a front wheel. The front fork 2 is attached to the front end of the vehicle body frame 5 via a head pipe 4. P is a resin cover mounted on the vehicle body frame 5, and a fuel tank is arranged inside.

The vehicle body frame 5 is a diamond frame, and an engine 6 is suspended and supported below the diamond frame.
A radiator 7 is attached to the front of the engine 6.
In addition, a rear swing arm 8 is provided at the rear of the body frame 5.
Is rotatably attached, and the rear wheel 9 is supported at the rear end thereof.

The vehicle body frame 5 is composed of left and right divided frames 10 and 11, and is formed by a bolt connection so as to have a substantially U-shaped cross section that opens downward as shown in FIG.

Each of the divided frames 10 and 11 is an integrally cast product by aluminum die casting, and has an average wall thickness of 2.5 mm,
It is most advantageous in terms of correlation with formability and strength.

Since the divided frames 10 and 11 are bilaterally symmetric, and the respective constituent parts are also formed symmetrically, the divided frame 10 (left side) will be described in principle in the following description. Therefore, in principle, the components of the right divided frame 11 are indicated by the same reference numerals as those of the left divided frame 10.

The split frame 10 extends below a front portion A, a main frame portion B that supports an engine, a fuel tank (not shown), and the like, a rear swing arm support portion C that is bent behind the main frame portion B, and a main frame portion B. The extended portion D. The main frame portion B has a substantially angled cross section, and the upper surface thereof is folded back in the horizontal direction to form an upper wall surface E. Further, on the mating surface of the upper wall surface E, a mating portion F having a standing wall shape is formed in the front-rear direction.

The front portion A is provided with a head pipe mounting portion 12 which is curved in a semi-cylindrical shape for mounting the head pipe 4. A coupling portion 13 having a large number of bosses for bolting is formed at the tip portion thereof. A duct 14 is formed slightly rearward of the head pipe mounting portion 12, and a boss portion 15 for bolting is formed in the recessed material.

The duct 14 takes in outside air while traveling,
It also serves as a heat exhaust port for the radiator 7 when the vehicle is stopped.

The extended portion D is formed by a truss member 16 protruding downward from the main frame portion B in a triangular shape, and an opening 17 is formed inside the truss member 16 and is attached to a bracket 16a in front of the truss member 16. It also serves as an exhaust port for the radiator 7 and a maintenance port for the engine head 6a.

An engine hanger 18 is formed at the lower end. A step portion is formed on the side surface of the main frame portion B in the length direction, and a character string is stamped on the step portion.

An opening 19 is formed on the rear side of the main frame portion B, and a mounting boss 20 and an engine hanger 21 are formed above and below the opening 19.

The rear swing arm support portion C is bent from the rear end portion of the main frame portion B and extends downward, and a pivot mounting portion 22 having a hole is formed in the center thereof, and an engine mounting hole is formed in the lower portion. 23, a mounting hole 24a for the step holder (not shown) and main stand mounting holes 25a, 25b are formed, and a cushion unit mounting portion 26 is formed on the upper part.

A boss portion 24b for mounting the other side of the step holder is formed on the upper portion of the cushion unit mounting portion 26.

A boss 27 is provided on the upper wall surface E along the front-back direction of the mating portion F.
To 31 and bulges 32 to 34 for reinforcement are formed between adjacent bosses.

The bosses 27 to 29 are reinforced by the ribs 35 to 39. Of these, ribs 35 and 36 and 37 and 38 are bulging portions.
It is formed by sandwiching 32 and 33, respectively. In the bulge 34,
A rib 40 is formed in the central portion.

A substantially U-shaped notch 41 is formed between the bosses 29 and 30 of the upper wall surface E so as to form an engine adjustment port when the left and right divided frames 10 and 11 are combined.

Further, a notch portion 42 for forming a cab adjusting opening is provided at a portion behind the notch portion 41 and separating the mounting bosses 30 and 31.

The cushion unit mounting portion 26 is thickly formed at the rear end edge of the cutout portion 42 for reinforcement, and the cushion unit shaft mounting portion 43 and the left and right divided frames 10 and
Eleven coupling portions 44 are formed.

A large number of ribs are formed on the inner side surface of the divided frame 10. Of these, the front portion A and the main frame portion B are formed with diamond-shaped ribs 45 that are substantially orthogonal to each other, and the ribs 45 intersect in a lattice shape over substantially the entire range of the main frame portion B to widen the rib cross section. In addition, it has a high strength structure similar to the honeycomb structure.

The rear swing arm support part C is the pivot mounting part 22
Mainly is a rib 46 radially formed with the center as a center, and a rib 47 partially intersecting with the rib is provided.

The density of these ribs is sparsely and densely arranged according to the required strength, and the pivot mounting portion 22 and the cushion unit mounting portion 26 are
The rear swing arm support portion C having the above is the densest and the main frame portion B is the roughest.

Further, a rib 48 continuous in a triangular shape is also formed in the extended portion D portion.

If necessary, a boss-shaped rib cross portion 49 as shown in FIG. 5 is formed at the intersection of each rib (for example, the rib 45). The rib cross portion 49 has a tip projecting further than the rib 45, and contributes to preventing sink marks after molding. By using this rib cross portion 49 as a mounting boss, it is possible to mount electrical components and the like.

Here, the mounting parts for the vehicle body frame 5 will be briefly described. First, seat rail 50 consists of main pipe 51 and reinforcement pipe.
52, and mounting ends 53 and 54 are provided on each. The mounting ends 53 and 54 include the mounting boss 20 and the connecting portion 44.
It corresponds to.

The upper mounting end 56 of the cushion unit 55 vertically installed in the space formed at the front end of the rear swing arm 8.
Is supported by the cushion unit mounting portion 26, the lower mounting end portion 57 is connected to the bottom surface of the rear swing arm 8 by a bell crank 58, and one end portion of a link 59 that is connected to the bell crank 58. Is fastened together with the main stand described later.

The main stand 60 has a pair of brackets 61 and 62, and mounting holes 63a and 63b facing the main stand mounting holes 25a and 25b and a stand mounting hole 63c are formed in each of them. In addition, cross pipes 63d and 63e are horizontally installed between the brackets 61 and 62. The upper end of the stand leg portion 64 is pivotally attached to the stand attachment hole 63c.

Next, the assembling of the vehicle body frame 5 and its mounting parts will be described. First, the head pipe 4 is put into the head pipe mounting portion 12, the divided frames 10 and 11 are aligned, and the joint portion 13 and the boss portions 15 and 27 to 31 are bolted. Further, in the seat rail 50, the mounting end portion 53 and the mounting boss 20 are bolted together, and the mounting end portion 54 is jointly tightened with a bolt for connecting the left and right coupling portions 44. As a result, a strong vehicle body frame 5 having a substantially U-shaped cross section that opens downward is assembled.

Further, the pivot portion 8a of the rear swing arm 8 is aligned with the pivot attachment portion 22 and pivotally coupled, and the end portion of the link 59 is jointly fastened to the vehicle body frame 5 using the cross pipe 63e. The upper mounting end 56 of the cushion unit 55 is inserted between the left and right cushion unit shaft attachment portions 43 and bolted.

Similarly, the brackets 61 and 62 are attached to the left and right main stand attachment holes 25a and 25b by the attachment holes 63a and 63b, respectively.

The ribs in the present embodiment are formed so that the rear swing arm support portion C portion is most densely formed. Therefore, the rear swing arm support portion C of the vehicle body frame 5 has the highest rigidity.

By the way, the rear swing arm support portion C is formed with the pivot attachment portion 22 and the cushion unit attachment portion 26, and the largest load is applied thereto via the rear swing arm 8 and the action unit 55.

However, by making the rib density so dense, it is possible to obtain a rigid structure that can sufficiently withstand the concentration of such a load.

Moreover, since a large number of ribs 46 are formed radially around the pivot mounting portion 22 and the ribs 47 intersecting with the ribs are provided in the vicinity of the pivot mounting portion 22, the stress concentration in the periphery of the pivot mounting portion 22 is the largest. The rigidity can be efficiently improved, and as a result, the entire rear swing arm support portion C can be made highly rigid.

On the other hand, the ribs are relatively rough in the portions other than the rear swing arm support portion C, and moreover, the ribs 45 are crossed in a lattice shape in substantially the entire range of the main frame portion B. The rigidity of the portion B is efficiently improved.

Therefore, even if the left and right divided frames 10 and 11 are formed to be thinner than the general casting limit by using aluminum die casting, the overall rigidity is sufficient. Moreover, by forming the main frame portion B in a substantially angle-shaped cross section symmetrical to each other, the intersecting ribs 45 can be easily formed inside thereof.

In addition, the body frame 5 is divided into the left and right divided frames 1
Since the downwardly-arranged generally U-shaped cross section is formed when the 0 and 11 are assembled, the lower portion of the vehicle body frame 5 is opened, and the entire weight can be further reduced by this amount. As a result, the entire frame can be made as light as possible, and at the same time, the required rigidity can be realized.

Moreover, the ribs 45, 46, 47 and 48 are formed on the respective divided frames 10,
Since it is provided inside 11, the appearance can be kept good.

[Effect of the Invention] The motorcycle body frame cast by die casting according to the present invention has a large number of ribs formed on the entire inner surface of each divided frame, and the distribution density thereof is made coarse and dense according to the required strength, Of these, the rib density of the rear swing arm support was made the highest.

In addition, a large number of ribs are formed radially around the pivot mounting portion, ribs that intersect a part of the radial ribs are provided in the vicinity of the pivot mounting portion, and the ribs are arranged in a grid pattern in substantially the entire range of the main frame portion. did.

Therefore, the rear swing arm support part, which receives the largest load during traveling, can be made highly rigid, and the rigidity around the pivot mounting part is provided in the vicinity of the pivot mounting part so as to intersect the radial rib and this part. With ribs
Further, it is possible to improve the efficiency efficiently by the intersection of these ribs.

On the other hand, the ribs are relatively rough in the parts other than the rear swing arm support part, and moreover, the ribs are crossed in a lattice shape over substantially the entire range of the main frame part. Is improved efficiently,
As a result, the entire frame can be made as light as possible.

Moreover, since the left and right divided frames are formed in substantially symmetrical angular cross-sections, the intersecting ribs can be easily formed inside them. Moreover, since the ribs formed inside each of the divided frames are not exposed, the appearance can be kept good.

Further, since the body frame is configured to have a downward substantially U-shaped cross section when the left and right divided frames are assembled, the lower portion of the body frame is opened, and the total weight can be further reduced by this amount.

Therefore, as the rigidity is improved by the high rigidity structure,
Since it is possible to mold the whole as thin as possible by using die casting, it is possible to reduce the overall weight as much as possible and to realize high rigidity to a certain degree at the same time,
It is possible to satisfy two conflicting requirements in the body frame.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a side view of a motorcycle, FIG. 2 is an exploded perspective view of a vehicle body frame and its mounting portion, and FIG. 3 is a vehicle body frame portion. Is a side view, FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3, and FIG. 5 is a perspective view of a main part. (Explanation of symbols) 4 ... Head pipe, 5 ... Vehicle frame, 8 ... Rear swing arm, 10.11 ... Split frame, 12 ... Head pipe mounting part, 22 ... Pivot mounting part, 26 ... Cushion unit mounting part, 45 ・ 46 ・ 48 …… rib, A …… front part, B …… main frame part, C …… rear swing arm support part, D …… extended part, E …… upper wall surface, F …… Matching department.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-178276 (JP, A) JP-A-62-26177 (JP, A) JP-A-59-77991 (JP, A) Actual development Sho-61- 291281 (JP, U) Actually opened 61-6084 (JP, U)

Claims (1)

[Claims] 1. A left and right split frame extending rearward from a head pipe, each of the left and right split frames respectively including a head pipe support portion, a main frame portion for supporting an engine, and a front end portion of a rear swing arm. A vehicle body frame for a motorcycle, wherein a rear swing arm support portion provided with a pivot mounting portion for pivotally supporting the body is integrally formed, and a reinforcing rib is formed, wherein each of the left and right divided frames is die-cast. The main frame portion is formed by molding so as to have a substantially angular cross section symmetrical to each other, and when the left and right divided frames are assembled, the body frame has a substantially downward U-shaped cross section, and the ribs are formed inside each divided frame. Depending on the required strength, it is arranged on the entire surface in a dense and dense manner, of which the rib density of the rear swing arm support is maximized. A number of ribs are formed densely and radially around the pivot mounting part, and ribs that intersect a part of the radial ribs are provided in the vicinity of the pivot mounting part. A body frame for a motorcycle, which is characterized by being formed into a shape.