JP3564867B2 - Motorcycle frame structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motorcycle frame structure, and more particularly to a motorcycle frame structure in which an upper tube and a lower tube are connected to a head pipe in a substantially parallel state.
[0002]
[Prior art]
Conventionally, as this type of frame structure, for example, there is one shown in FIG.
In the figure, an upper tube b extending obliquely downward from here is connected to an upper end of a head pipe a through which a steering shaft is inserted, and a body frame c is connected to a rear end of the upper tube b. Have been. Below the upper tube b, a lower tube d connecting the head pipe a and the body frame c is provided substantially in parallel with the upper tube b. The lower tube d includes a front lower tube d1 connected to the head pipe a, a front suspension d2 welded to the lower surface thereof, a rear suspension d3 welded to the rear end of the lower tube d1, and a rear suspension d3. d3 and a lower tube d4 having both ends welded to the body frame c.
[0003]
The engine e is suspended by a front suspension portion d2 and a rear suspension portion d3 of the lower tube d, and two upper and lower suspension portions c1 and c2 of the body frame c.
As described above, in the conventional frame structure, the engine e is suspended by the lower tube d and the body frame c, whereby the engine acts as a strength member to secure the strength of the frame structure. It has become something.
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned conventional frame structure, as shown in FIG. 7, the upper tube b and the lower tube d have substantially the same outer diameter, so that an attempt is made to obtain sufficient strength as the entire frame structure. If the outer diameter of the upper tube b is too large, also the outer diameter dimension of the lower tube c is a problem that too small.
[0005]
That is, in the conventional frame structure, since the outer diameter of the upper tube b set for securing the strength is large, there is a disadvantage that the capacity of the fuel tank t located above the upper tube b is reduced.
Further, by the outer diameter dimension of the upper tube b is increased, the width of the knee grip is spread in rider, good with riding position not be obtained occurs, steering stability goes back up the center of gravity of the entire vehicle There is also the problem of lacking.
[0006]
On the other hand, the lower tube c as described above, the need to suspend the engine, the outside diameter dimension of approximately identical to the upper tube b it is impossible to have a strength to a sufficient margin. However, although it caused to increase from the current outside diameter dimension of the lower tube c securing strength can some a, this is a new problem of causing the vehicle overall weight increase.
[0007]
The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is possible to secure the strength of the lower tube without increasing the weight of the entire vehicle body, and to obtain a good riding position and steering stability. An object of the present invention is to provide a motorcycle frame structure that can be used.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above-mentioned problems.
That is, the present invention includes a pair of left and right upper tubes connecting a head pipe through which a steering shaft is inserted and a body frame behind the head pipe, and a pair of left and right lower tubes each having a front end connected to the head pipe. In a frame structure of a motorcycle in which a suspension portion for suspending an engine is provided between the lower tube and the body frame, and the engine is suspended by the suspension portion, the engine is used as a strength member. the diameter larger than the outer diameter of the upper tube, said pair of right and left upper tubes are connected by bridges to connect the two ends to the connecting point set via the same distance apart from the head pipe, the engine engine The lower tube suspension that suspends the front of the block, and the body Provided below the frame generally along the line connecting the suspension unit for suspending a rear portion of the engine block, connecting the vicinity of the connecting point between the bridge of the the vicinity of the suspension portion of the lower tube upper tube tension And a member.
[0009]
According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a bridge having both ends connected to a connection point set on each upper tube through the same distance from the head pipe , A tension member provided substantially along a line connecting a suspension portion of a lower tube for suspending a front portion and a suspension portion for suspending a rear portion of an engine block provided at a lower portion of the body frame ; has become that a tension member connecting the vicinity of the suspension rack portion of the the neighborhood lower tube.
[0010]
Further, the invention according to claim 3 is configured such that the engine block is suspended between the suspension portion of the lower tube and the suspension portion of the body frame, and the lower tube is formed of a rear lower tube extending from the suspension portion suspending the engine block to the body frame . the outer diameter, and is obtained by a small fence than the outer diameter of the front lower tube leading to the head pipe from the suspension portion.
[0011]
Then, the in the first aspect of the present invention, because that is the one having an outer diameter dimension that the lower tube is greater than the upper tube, it is possible to secure a sufficient strength capable of supporting the weight of the engine, moreover upper tube can reduce the outer diameter dimension of the upper tube by the intensity increase of the lower tube, while maintaining a sufficient strength as a whole frame structure, it is possible to avoid an increase in weight of the whole vehicle body. Further, a decrease in the outer diameter dimension of the lower tube, while it is possible to increase the capacity of the fuel tank, it is possible to reduce the width of the knee grip in rider can take a good riding position At the same time, the center of gravity of the entire vehicle body is lowered, so that running stability is improved.
[0012]
In the invention of claim 2, since the tension member connected to the upper tube suspension rack portion near the lower tube are connected, but the load from the engine by the lower tube, via a tension member The upper tube can be dispersed and supported, and the engine can be suspended more reliably.
[0013]
Further, in the invention of claim 3, wherein the outer diameter dimension of the portion from the suspending portion to the head pipe by setting the large becomes the value, it is possible to secure the strength that can sufficiently support the load from the engine , also it is possible to reduce the weight of the entire frame by reducing the outer diameter dimension of the portion extending to the body frame from the suspension portion.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view showing the entire structure of a motorcycle frame structure according to an embodiment of the present invention, FIG. 2 is an enlarged side view of the one shown in FIG. 1, FIG. 3 is a plan view of the one shown in FIG. 2 is a bottom view of what is shown in FIG. 2, and FIG. 5 is a sectional view taken along line AA of FIG.
[0015]
In each of the drawings, a head pipe 2 is provided at a front end of a frame 1 forming a skeleton of a body of a motorcycle M. A steering shaft is inserted through the head pipe 2 and a front shaft supported by the steering shaft is provided. The front wheel Hf is rotatably supported by the fork Ff.
The front ends of a pair of left and right upper tubes 3a and 3b extending diagonally downward toward the rear are fixed to the upper end of the head pipe 2 as shown in FIGS. A fuel tank T is provided above. A body frame 4 is fixed to the rear ends of the upper tubes 3a and 3b, and a swing arm SA that rotatably supports the rear wheel Hr is mounted on the body frame 4 around a pivot SA1. The cushion unit Cu is swingably supported in a vertical direction, and a rear end of the cushion unit Cu is connected via a predetermined link member.
[0016]
On the other hand, a pair of lower tubes 5a, 5b is provided below the upper tubes 3a, 3b so as to be substantially parallel to the upper tubes 3a, 3b in a side view. The lower tubes 5a and 5b have their front ends fixed to the lower part of the head pipe 2 and their rear ends fixed to the body frame 4, respectively, and are configured as follows.
That is, the lower tubes 5a and 5b in this embodiment include a front lower tube 51 having a front end connected to the head pipe 2, a front suspension portion 52 welded to the lower surface thereof, and a rear portion of the front lower tube 51. A rear suspension portion 53 welded to the end portion and a rear lower tube 54 and a connecting pipe 55 integrally formed with the rear suspension portion 53 are provided. The frame 4 is welded.
[0017]
Each of the upper tubes 3a, 3b and the front lower tubes 5a, 5b has a cylindrical shape, and the front lower tube 51 has an outer diameter of the upper tube 3a as shown in FIG. is formed on the larger becomes the outside diameter, the front lower tube 5a is formed in the outer diameter dimension becomes smaller from the rear lower tube 5d.
Further, a bridge 7 is connected between the left and right upper tubes 3a and 3b as shown in FIGS. Each connection point between each of the upper tubes 3a, 3b and the bridge 7 is set to be at the same distance from the head pipe 2, and the center of the head pipe and each connection point are each vertex of an isosceles triangle. (See FIG. 3).
[0018]
Tension members 8a and 8b are connected between the upper tubes 3a and 3b and the lower tubes 5a and 5b. The upper ends of the tension members 8a, 8b are connected to the vicinity of the rear part of the connection point between the upper tubes 3a, 3b and the bridge 7, and the lower ends are the rear ends of the left and right front lower tubes 51, 51, respectively. , That is, near the front portions of the rear suspension portions 53, 53. In the drawings, 9a and 9b are reinforcing pipes connected between the lower tubes 5a and 5b and the bridge, and 10 is a bracket for attaching the front end of the cushion unit Cu. Are linked.
[0019]
In the motorcycle frame structure configured as described above, the engine 6 including the engine block 6a and the cylinders 6b and 6c is suspended by the lower tubes 52 and 53 and the body frame 4 as shown in FIG. The engine shown here is a V-type engine in which cylinders 6b and 6c are disposed before and after an engine block 6a. A front cylinder 6b is provided in a front suspension portion 52 of a lower tube 5a, and an engine block 6a is provided in a rear suspension portion 53 and a body. The frame 4 is suspended by being connected to the suspension portions 4a and 4b.
[0020]
Therefore, the load from the engine 6 is applied to the lower tubes 5a and 5b, but the lower tubes 5a and 5b are set to have larger outer diameters than the upper tubes 3a and 3b, and have sufficient strength in advance. Therefore, the load from the engine 6 can be reliably supported. In this embodiment, the load from the engine 6 is dispersed to the upper tubes 3a, 3b via the tension members 8a, 8b provided near the rear suspension portion 53 for suspending the engine block 6a, and The loads related to 5a and 5b are reduced.
[0021]
However, since the upper tubes 3a and 3b are smaller in diameter than conventional ones, the strength of each of the upper tubes 3a and 3b is inferior to the conventional ones, but the bridge 7 is connected between the upper tubes 3a and 3b. Therefore, the overall strength of the structure including these is superior to the conventional upper tubes 3a, 3b, and the upper ends of the tension members 8a, 8b are set near the bridge 7. Therefore, the upper tubes 3a and 3b and the bridge 7 can reliably support the load applied via the tension members 8a and 8b. Since the engine 6 also functions as a strength member of the entire frame structure, even if the diameter of the rear lower tube 54 located between the rear suspension portion 53 and the body frame 4 is reduced, no problem in strength occurs. By reducing the diameter of the rear lower tube 54, the weight of the entire vehicle body can be reduced.
[0022]
Further, since the diameter of the upper tubes 3a and 3b is reduced as described above, the volume of the fuel tank T installed above can be increased accordingly. Furthermore, since the width of the knee grip by the rider is reduced by reducing the diameter of the upper tubes 3a, 3b, a comfortable riding position can be obtained, and the weight reduction along with the reduction in the diameter of the upper tubes 3a, 3b allows the entire vehicle body to be reduced. The steering center can be improved because the center of gravity is lowered.
[0023]
In the above embodiment, the front lower tube 51 has a circular cross-sectional shape as shown in FIG. 5A, but the lower surface of the front lower tube 51a is formed as shown in FIG. 5B. It may be formed in a flat plate shape. In this case, welding between the front suspension portion 52 and the lower tubes 5A and 5B can be performed more easily.
[0024]
【The invention's effect】
Or as described, the frame structure of the motorcycle according to the present invention, since adapted to ensure the strength of the lower tube is formed on an outer diameter dimension becomes larger the lower tube from the upper tube, securely suspending the engine can do. In addition, since the diameter of the upper tube can be reduced as the strength of the lower tube increases, the capacity of the fuel tank can be increased. Furthermore, the width of the knee grip can be reduced by the rider, so that a comfortable riding position can be obtained, and the lowering of the center of gravity of the entire vehicle body greatly improves steering stability.
[0025]
In addition, if the left and right upper tubes are connected by a bridge and the vicinity of the connection point and the vicinity of the engine suspension in the lower tube are connected by a tension member, the load from the engine can be transferred not only to the lower tube but also to the upper tube. It is possible to support the tubes in a dispersed manner, and it is possible to give a margin to the suspension state of the engine.
Furthermore, if the portion of the lower tube from the suspension portion that does not directly contribute to the suspension of the engine to the body frame is miniaturized, the weight of the entire vehicle body can be reduced.
[Brief description of the drawings]
FIG. 1 is a side view showing an entire configuration of a frame structure of a motorcycle according to an embodiment of the present invention.
FIG. 2 is an enlarged side view of what is shown in FIG.
FIG. 3 is a plan view of what is shown in FIG. 2;
FIG. 4 is a bottom view of what is shown in FIG.
FIG. 5 is a sectional view taken along the line AA of FIG.
FIG. 6 is a side view showing the entire structure of a conventional motorcycle frame structure.
FIG. 7 is a sectional view taken along the line BB of FIG.
[Explanation of symbols]
2 head pipe 3a, 3b upper tube 4 bodywork 5a, 5b lower tube 6 engine 7 bridge 8a, 8b tension member 52, 53 suspension rack section

Claims (1)

A pair of left and right upper tubes connecting a head pipe through which a steering shaft is inserted and a body frame located behind the head pipe; and a pair of right and left lower tubes each having a front end connected to the head pipe; In a frame structure of a motorcycle in which a suspension portion for suspending an engine is provided on a frame, and the engine is used as a strength member by suspending the engine on the suspension portion.
Make the outer diameter of the lower tube larger than the outer diameter of the upper tube,
The pair of left and right upper tubes are connected by a bridge connecting both ends to a connection point set at the same distance from the head pipe ,
The suspension portion of the lower tube substantially along a line connecting a suspension portion of a lower tube that suspends a front portion of an engine block of the engine and a suspension portion that is provided at a lower portion of a body frame and suspends a rear portion of the engine block. A frame structure for a motorcycle, comprising: a tension member connecting the vicinity of the upper tube and the vicinity of a connection point of the upper tube with the bridge .

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