JPH0735153B2 - Motorcycle with fuel tank - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle provided with a fuel tank, and more particularly to an automatic vehicle provided with a fuel tank for reducing vibration of the fuel tank due to an internal combustion engine to improve riding comfort. It concerns motorcycles.

[Prior Art] For example, in a motorcycle, an internal combustion engine is mounted on a vehicle body frame, a fuel tank is attached to the vehicle body frame above the internal combustion engine, and a rider is seated behind the fuel tank. There is a model sheet attached.

Since this fuel tank is attached to the vehicle body frame, the invented vibration is transmitted from the vehicle body frame to the fuel tank when the internal combustion engine is driven, and the ride comfort of the rider is impaired.

[Problems to be Solved by the Invention] In order to reduce the vibration of the fuel tank, a so-called dynamic damper for vibration damping disclosed in Japanese Utility Model Laid-Open No. 59-7384 filed by the applicant is used. Can be considered. When using this dynamic damper, it is effective to provide it in a portion of the fuel tank that resonates with the internal combustion engine. By the way, some fuel tanks have a recess that straddles the vehicle body frame. Since this fuel tank is designed to be recessed toward the inside of the tank so as to straddle the vehicle body frame, the vertical cross section has an inverted U shape. The concave portion forming the shape vibrates in the axle direction, and the amplitude becomes larger toward the lower end of the concave portion.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a motorcycle including a fuel tank that suppresses vibration of the fuel tank so as not to resonate with vibration of the internal combustion engine and that improves ride comfort. There is.

[Means for Solving the Problems] In order to solve the problems described above, the present invention relates to a fuel in which a fuel tank is attached to a vehicle body frame on which an internal combustion engine is mounted, and a saddle type seat is attached to the rear of the fuel tank. In a motorcycle including a tank, the fuel tank has a recess that is recessed inward of the tank and straddles the body frame, and the left and right inner walls that form the recess at the front of the tank of the fuel tank are supported by the body frame, and A substantially central rear portion of a fuel tank is supported by the vehicle body frame, and dynamic dampers each including an elastic body and a weight attached to the elastic body are attached to outer surfaces of left and right inner walls forming a recessed portion of the tank rear portion. It is characterized by that.

[Operation] In the present invention, the vibration due to the driving of the internal combustion engine is transmitted from the vehicle body frame to the fuel tank, the recess of the fuel tank vibrates in the vehicle width direction, and the amplitude tends to increase toward the lower end of the recess. As for the vibration of the front portion of the tank, since the left and right inner walls forming the concave portion of the front portion of the tank are supported by the vehicle body frame, it is possible to suppress the concave portion of the fuel tank from vibrating in the vehicle width direction.

Further, since the tank rear part of the fuel tank has a substantially central portion supported by the vehicle body frame, the recess of the fuel tank vibrates in the vehicle width direction, and the amplitude tends to increase toward the lower end of the recess. The vibration at the rear of the tank is effectively absorbed and damped by the dynamic dampers attached to the outer surfaces of the left and right inner walls forming the recess at the rear of the tank.

Therefore, the vibration of the fuel tank is suppressed, and it is possible to reduce the transmission of the vibration from the fuel tank to the rider seated on the saddle type seat attached to the rear side of the fuel tank during the knee grip. The riding comfort is improved.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a motorcycle to which the invention is applied, and FIG.
FIG. 4 is a side view showing a mounting state of the fuel tank, FIG. 3 is a bottom view of the fuel tank, and FIG. 4 is a sectional view taken along line IV-IV of FIG.

In the drawings, reference numeral 1 is a vehicle body frame, and a head pipe 2 constituting the vehicle body frame 1 is rotatably supported by a front fork 4 having front wheels 3 suspended thereon. A pair of left and right down tubes 5 and a tank rail 6 are connected to the head pipe 2, and a seat rail 7 is connected to the tank rail 6 so as to extend rearward of the vehicle body.
A backstay 8 connects the rear end of the down tube 5 and the seat rail 7.

Further, an internal combustion engine 9 is attached to the pair of left and right down tubes 5.
Is mounted so as to be hung from both sides, and a fuel tank 10 is mounted above the internal combustion engine 9 so as to cover the front side portions of the pair of left and right tank rails 6 and the seat rail 7. A saddle-type seat 12 on which a rider 11 straddles is disposed behind the fuel tank 10 in a detachable manner on the seat rail 7. This seat 12 is a synthetic resin seat bottom 13
And a cushion material 14 placed on the seat bottom 13 and made of, for example, urethane foam, and a cushion material 14
And a seat leather 15 that surrounds and supports the seat bottom 13, and the front side of the seat 12 covers the rear part of the fuel tank 10. Side covers on both lower sides of seat 12
Covered with 16. The rider 11 straddles the seat 12 and rides on both sides of the bent knee 11a on both sides of the rear portion of the fuel tank 10.

The fuel tank 10 is superposed on the outer panel 17 and the inner panel 18 in a monaca shape, and has a joint flange portion 17 at the peripheral edges thereof.
It is formed by welding a and 18a. This fuel tank 10 has a recess 100 that is recessed inwardly of the tank and straddles the tank rail 6 that constitutes the vehicle body frame 1. Thus, the fuel tank 10 is recessed inwardly of the tank and straddles the tank rail 6. The vertical cross section is an inverted U shape.

A pair of front side mounting portions 19 are provided on the left and right inner walls 100a, 100b forming the recess 100 of the tank front portion 10a of the fuel tank 10,
The front side mounting portion 19 is a semicircular engagement portion 19a having an opening on the front side.
have. The engagement portion 19a of the front side attachment portion 19 is engaged with and attached to a cross pipe 21 provided between a pair of brackets 20 provided on the front side of the vehicle body.

On the other hand, on the rear side of the fuel tank 10, a rear side mounting portion 23 having a mounting screw insertion hole 22 is provided. That is, the rear mounting portion 23
Is the rear flange portion 17 of the outer panel 17 and the inner panel 18.
The a and 18a extend rearward and are welded to the inner panel 18 side. In this rear side mounting portion 23, the bolt 25 is inserted into the mounting screw insertion hole 22 via the washer 24, and the nut welded to the bracket 26 provided between the pair of seat rails 7 is welded.
It is screwed to 27 and fastened. In this way, the bracket 2 is located at the approximate center of the seat side tank rear portion 11b of the fuel tank 10.
It is supported by a tank rail 6 which constitutes the vehicle body frame 1 via 6.

The fuel tank 10 is formed so that the tank front portion 10a has a large capacity and the tank rear portion 10b has a small capacity.The tank front portion 10a is locked to the vehicle body, but the tank rear portion 10b is fastened and fixed to the vehicle body. Since the outer panel 17 and the inner panel 18 are attached to each other, the rigidity of the tank rear portion 10b is higher than that of the tank front portion 10a even if the outer panel 17 and the inner panel 18 are formed to have the same thickness. Therefore, the fuel tank 10 is
The natural frequency of a is low, and the natural frequency of the tank rear portion 10b is high, which is close to the natural frequency of the internal combustion engine 9.

In this fuel tank 10, dynamic dampers 28 for vibration damping are attached to the outer surfaces 100c and 100d of the left and right inner walls forming the recess 100 of the tank rear portion 10b. The mounting position of this dynamic damper 28 is located near the knee head 11a of the rider 11 in the tank rear portion 10b. The dynamic damper 28 includes an elastic body 28a made of rubber or the like and a weight 28b made of an iron plate or a lead plate attached to the elastic body 28a. Then, the dynamic damper 28 uses the elastic body 28a with an adhesive or the like for the fuel tank 10
It is fixed to the inner panel 18 of the tank rear portion 10b.

Next, the operation of this embodiment will be described.

When the internal combustion engine 9 is driven, vibration is generated in the internal combustion engine 9, and this vibration is transmitted to the fuel tank 10 via the down tube 5 and the tank rail 6 of the vehicle body frame 1 and vibrates the fuel tank 10. .

In this way, the vibration caused by the driving of the internal combustion engine 9 is transmitted from the body frame 1 to the fuel tank 10, and the recess of the fuel tank 10 is
100 vibrates in the vehicle width direction, and the amplitude tends to increase toward the lower end of the recess 100.
Vibration of the left and right inner walls forming the recess 100 of the tank front portion 10a
Since the 100a and 100b are supported by the vehicle body frame 1, the recess 100 of the fuel tank 10 can be suppressed from vibrating in the vehicle width direction.

Further, since the tank rear portion 10b of the fuel tank 10 has a frequency close to the natural frequency of the internal combustion engine 9, the vibration resonates with the vibration of the internal combustion engine 9 and tends to increase.

Moreover, since the recess 100 of the fuel tank 10 is recessed toward the inside of the tank so as to straddle the tank rail 6, the recess 10
0 vibrates in the vehicle width direction, and the amplitude tends to increase toward the lower end of the recess 100.

However, this vibration is caused by the weight 28b of the dynamic damper 28 that vibrates because the dynamic dampers 28 are attached to the left and right inner wall outer surfaces 100c and 100d forming the recess 100 of the tank rear portion 10b of the fuel tank 10. Is consumed by and the vibration of the tank rear portion 10b is damped.

Therefore, the rider 11 uses the knee grip 11a and the rear part 1 of the tank.
Although the passenger is riding with 0b sandwiched from both sides, the vibration of the tank rear portion 10b is attenuated, so that the transmission of the vibration to the knee grip 11a is reduced and a good riding feeling can be obtained.

The dynamic damper 28 can freely adjust the size, shape and spring constant of the elastic body 28a, and the size, shape and weight of the weight 28b according to the shape and vibration characteristics of the fuel tank 10. The high frequency resonance of 9 can be absorbed.

Further, in the above-described embodiment, the dynamic damper 28 is provided at the symmetrical position of the inner panel 18 near the seat rail 7.
Although one piece may be attached or two or more pieces may be attached, the elastic body 28a and the weight 28b may be attached to the fuel tank 10 as described above.
The same effect can be obtained by setting according to the shape and the vibration characteristics of the. Also, the dynamic damper 28 is used for the fuel tank 10.
It is placed on the back side of the so that it cannot be seen from the outside and the appearance is not damaged.

Further, in the case where the seat 12 has a shape that covers the rear portion of the fuel tank 10, the vibration of the fuel tank 10 is suppressed, so that the effect of reducing the vibration of the seat itself can be achieved.

[Advantages of the Invention] As described above, according to the present invention, the vibration due to the driving of the internal combustion engine is transmitted from the vehicle body frame to the fuel tank, the concave portion of the fuel tank vibrates in the vehicle width direction, and further, the amplitude increases toward the lower end of the concave portion. However, the vibration of the front part of the tank suppresses the recess of the fuel tank from vibrating in the vehicle width direction because the left and right inner walls that form the recess in the front part of the tank are supported by the vehicle body frame. To be

In addition, a substantially central portion of the rear portion of the fuel tank is supported by the vehicle body frame, and dynamic dampers including elastic members and weights attached to the elastic members are attached to the outer surfaces of the left and right inner walls forming the recessed portion of the tank rear portion, respectively. Therefore, the vibration due to the driving of the internal combustion engine is transmitted from the body frame to the fuel tank, the fuel tank vibrates and the vibration at the rear of the tank resonates with the vibration of the internal combustion engine, and the concave portion straddling the body frame of the fuel tank extends in the vehicle width direction. Even if the vibration vibrates and the amplitude increases toward the lower end of the recess, this vibration is effectively absorbed and damped by the dynamic dampers attached to the outer surfaces of the left and right inner walls forming the recess in the rear portion of the fuel tank. The vibration of the fuel tank can be effectively reduced with a simple structure.

Therefore, the rider rides with the knee grip sandwiching the rear part of the tank from both sides, but the influence of vibration from the fuel tank is reduced and the ride appearance is improved.

[Brief description of drawings]

FIG. 1 is a side view of a motorcycle to which the invention is applied, and FIG.
FIG. 4 is a side view showing a mounting state of the fuel tank, FIG. 3 is a bottom view of the fuel tank, and FIG. 4 is a sectional view taken along line IV-IV of FIG. 1 …… Body frame, 5 …… Down tube 6 …… Tank rail, 7 …… Seat rail 9 …… Internal combustion engine, 10 …… Fuel tank 10a …… Tank front, 10b …… Tank rear 11 …… Rider, 11a …… Knee grip 12 …… Seat, 17 …… Outer panel 18 …… Inner panel, 19 …… Front mounting part 23 …… Rear mounting part, 28 …… Dynamic damper 100 …… Recessed part, 100a, 100b …… Inner wall 100c, 100d …… Outer surface of inner wall

Claims (1)

[Claims] 1. A motorcycle comprising a fuel tank mounted on a vehicle body frame having an internal combustion engine and a saddle-type seat mounted behind the fuel tank, wherein the fuel tank is recessed inwardly of the tank. While having a recess extending across the vehicle body frame, the left and right inner walls forming the recessed portion of the tank front portion of the fuel tank are supported by the vehicle body frame, substantially the center of the tank rear portion of the fuel tank is supported by the vehicle body frame, A motorcycle comprising a fuel tank, characterized in that dynamic dampers each comprising an elastic body and a weight attached to the elastic body are attached to the outer surfaces of the left and right inner walls forming the recessed portion at the rear of the tank.