JPS62125965A - Car body frame of saddling type four-wheel car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a vehicle body used in a straddle-type four-wheeled vehicle in which a straddle-type driver's seat is provided above an engine mounted near the center of the vehicle body frame. It's about frames.

(Background of the Invention) There have conventionally been straddle-type four-wheeled vehicles for driving on rough terrain that are equipped with wide, ultra-low-pressure tires. In this type of vehicle, a saddle-type driver's seat is installed above the engine mounted near the center of the vehicle body.
You ride by straddling this driver's seat. For this reason, there was a problem in that the center of gravity tended to be high. Furthermore, it is desirable that the vehicle body frame be lightweight and highly rigid.

Conventional body frames of this type can be roughly divided into the following three types. Namely, a) a large-diameter main pipe extending diagonally downward and backward from the upper support part of the steering shaft, so that the load is concentrated on this main pipe, and b) a main pipe with two small-diameter trees as well. There are three types: one that divides the load into two pipes and distributes the load between the two, and (C) one that does not have a clear main pipe and uses only a large number of pipes to distribute the stress over the whole. However, the above types a) and b) are based on the center of gravity. In addition, in type C), the pipe structure is complicated, and the number of reinforcing gussets that are fixed to the joints between the pipes increases.

Furthermore, in each of the conventional types mentioned above, when a road obstacle hits the lower part of the car body frame, the effect tends to spread to the entire car body frame, and there is also the problem that the car body frame is easily distorted due to contact with the obstacle. there were.

(Purpose of the invention) The invention was made in view of these circumstances, and is suitable for lowering the center of gravity, provides high rigidity with a relatively simple structure,
To provide a body frame for a straddle-type four-wheeled vehicle that requires fewer gussets and is less prone to deformation due to collision with obstacles.

(Structure of the Invention) According to the present invention, this object is achieved in a straddle-type four-wheel vehicle that includes an engine mounted near the center of the vehicle body frame and a straddle-type driver seat disposed above the engine. The vehicle body frame includes a pair of left and right lower tubes passing under the engine in the front-rear direction, an upper tube passing under the driver's seat in the front-rear direction, and an appropriate vertical tube connecting these lower tubes and the upper tube. This is achieved by a body frame for a straddle-type four-wheeled vehicle, characterized in that the lower tube has a larger diameter than the upper tube.

That is, the large-diameter lower tube has the role of a backbone, and the loads of other tubes are mainly concentrated on this lower tube.

(Embodiment) Fig. 1 is a partially sectional side view of an embodiment of the present invention, and Fig.
3 is a side view of the vehicle body frame, FIG. 4 is a plan view, and FIG. 5 is a front view.

In FIGS. 1 and 2, reference numeral 10 denotes a vehicle body frame, and this frame 10 has a pair of left and right large-diameter tubes 12 (12a, 12b) whose rear parts are bent diagonally upward and rearward, and which are arranged at approximately right angles when viewed from the side. A pair of bent left and right front tubes 14 (1
4a, 14b) and a pair of left and right front upper tubes 16 (
16a, 16b) and the rear upper tube 18 (18a, 1
8b), front tube 20, and rear tube 22 (2
2a.

22b). The front upper tube 16 and the rear upper tube 18 have a smaller diameter than the lower tube 12.
It is desirable that the diameter be 1.5 to 2.0 times that of the rain tube 16.18. The front end of the front tube 14 is fixed to a cross tube 24 that connects the front end of the lower tube 12,
The rear end is fixed to the intermediate portion of the front tube 20.

The upper end of the front tube 20 is fixed to a cross tube 26 that connects the front upper tube 16, and the lower end is fixed to the lower tube 12.
It is fixed to a cross tube 28 that connects the two.

A cross tube 30 is fixed to the front end of the front upper tube 16, and its left and right ends and the front tube 14 are connected by a shock absorber tower 32 (32a, 32b). Further, the front tubes 14 are interconnected by a cross tube 33 near the lower edge of the tower 32, and as a result, the tower 32 and the cross tubes 30, 33 form a closed loop having an inverted trapezoid in front view (see FIG. 5). Rear upper tube 1
8 is fixed to the rear end of the lower tube 12 and the upper end of the rear tube 22, and its front end is fixed to the rear end of the front upper tube 16 via the cross tube 34.

36 (36a, 36b) are a pair of left and right front wheels with wide ultra-low pressure tires, which are supported by a modified double wishbone type suspension system. That is, the front wheel 36
The upper part of the knuckle bracket (not shown) is connected to the front tube 14 by an upper arm 38 that is approximately A-shaped in plan view, and the lower part (±front drive shaft 40 (only one shown) and tension rod 42 (42a, 42b) It is connected with.

The inner end of the front drive shaft 40 is connected via a cross joint to a front differential 44 fixed to the lower tube 12, and the outer end is connected via a cross joint to a spindle 46 rotatably held by a knuckle bracket. are connected. Further, a cylindrical shock absorber 48 (48a, 48b) is interposed between the upper arm 3 and the upper end of the shock absorber tower 32.

50 (50a, 50b) are rear wheels with wide ultra-low pressure tires. The rear wheel 50 is fixed to a rear axle 54 that protrudes from a rear differential 52, and the rear differential 52 is integrated with a swing arm 56. This swing arm 56 has its front end vertically swingably attached to a bearing bracket 57 (57a, 57b) located at the lower end of the rear tube 22, and is resiliently supported by a shock absorber 55 (not shown). There is.

58 is an engine mounted near the center of the vehicle body frame 10. The rotation of the output shaft 60 of the engine 58 is transmitted to the rear differential device 52 via a universal joint 62 and a rear drive shaft 64.
can be conveyed to. Note that the rear drive shaft 64 is the swing arm 56
It is inserted into the left cylinder.

A distributor a66 extending downwardly across the output shaft 60 is fixed to the engine 58. This distributor 66 houses a gear group 70 that transmits the rotation of the engine output shaft 60 to the distributor output shaft 68.

This rotation of the distributor output shaft 68 is transmitted to the front differential device 44 via the universal joint 72, the front drive shaft 74, and the universal joint 76.

In the figure, 78 (78a, 78b) is a pair of left and right footrests, 80 is a carburetor, 82 is an intake air purifier, and 84 is an engine 5.
8 is the exhaust pipe passing on the right side, 86 is the exhaust muffler, 88 is the front fender, 90 is the rear fender, 92 is the steering bar handle,
Reference numeral 94 denotes a straddle-type driver's seat located above the engine 58 and long in the front-rear direction.

According to this embodiment, the output of the engine 58 is transferred to the distributor 66.
The power is distributed between the front wheel drive force and the rear wheel drive force. The front wheel driving force is transmitted to the gear group 70 of the distributor 66, the front drive shaft 74, and the front differential 44, and is further transmitted from the front differential 44 to the left and right front wheels 36 via the left and right front drive shafts 40. It will be done. The rear wheel driving force is transmitted to the left and right rear wheels 50 via the rear drive shaft 64, the rear differential 52, and the rear axle 54, and the rear wheels 50 rotate at the same speed as the front wheels 36.

In this embodiment, the upper tube is composed of a front upper tube 16 and a rear upper tube 18, but the upper tube of the present invention may be integrated in the front-rear direction. Although it is desirable to provide a pair of left and right upper tubes, the present invention also includes a pair of upper tubes made of lumber. Further, in the non-embodiment, the rear end of the lower tube 12 was bent obliquely upward and backward, and the rear end was fixed to the upper tube 18, but the present invention also includes a structure in which the rear end of the lower tube is connected with another vertical tube.

(Effects of the Invention) As described above, in the present invention, the lower tube is made larger in diameter than the upper tube, and the two are appropriately connected by a vertical tube or the like, so that the center of gravity can be lowered.

In addition, since the lower tube serves as the backbone of the entire vehicle frame, it is easy to increase the rigidity of the entire vehicle frame by utilizing the high rigidity of the lower tube, and the structure is simple and the number of gussets can be reduced. Furthermore, even if an obstacle hits the lower tube, the lower tube itself is highly rigid, so deformation is less likely to occur, and the vehicle frame is less likely to go awry.

[Brief explanation of drawings]

FIG. 1 is a partially sectional side view of one embodiment of the present invention, and FIG.
3 is a side view of the vehicle body frame, FIG. 4 is a plan view, and FIG. 5 is a front view. 10...Vehicle body frame. 12...Lower tube, 16...Front upper tube, 18...Rear upper tube, 20...Front tube, 22...Rear tube, 58...Engine, 94...Saddle Riding type driver seat.

Claims (3)

[Claims] (1) An engine mounted near the center of the vehicle body frame,
In this straddle-type four-wheel vehicle equipped with a straddle-type driver's seat disposed above the engine, the body frame includes a pair of left and right lower tubes passing below the engine in the front-rear direction, and a straddle-type driver's seat arranged above the engine. A saddle riding system comprising an upper tube passing under the seat in the front-rear direction, and an appropriate vertical tube connecting the lower tube and the upper tube, the lower tube having a larger diameter than the upper tube. The body frame of a four-wheeled vehicle. (2) A body frame for a straddle-type four-wheeled vehicle according to claim 1, wherein the lower tube has an outer diameter 1.5 to 2.0 times that of the upper tube. (3) The straddle-type four-wheeled vehicle according to claim 1 or 2, wherein the rear part of the lower tube is bent diagonally upward and rearward, and the rear end is connected to the upper tube. car body frame.