JPS58141983A - 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] This invention allows a pair of left and right rear wheels to be movable downward.

A vehicle width has been proposed in which a pair of left and right rear wheels are attached to both ends of an axle, and the front end of the axle is held movable up and down by a single rear arm that is pivoted to the vehicle body frame. With this type of vehicle width, both wheels move up and down as one, so a large torsional stress is applied to the rear arm. In particular, in tricycles that are equipped with ultra-low-pressure tires on the rear wheels and rotate both wheels at the same speed without using a differential, when turning, the driver's weight shift causes the inner rear wheel in the direction of the turn to move against the road surface. However, in this type of vehicle, the torsional stress applied to the rear arm becomes even greater. In addition, even in tricycles and four-wheeled vehicles that use a differential device to give a difference in rotational speed between the left and right rear wheels, both wheels are held by a single rear arm so that they move up and down as one, as described above. Since the impact exerted on the rear wheels by uneven road surfaces differs between the left and right wheels, a large torsional force is applied to the rear arm.

Therefore, the rear arm needs to have high rigidity against torsional force, but in order to reduce the weight of the vehicle and improve driving performance, it is also necessary to reduce the weight of the rear arm.

This invention was made in view of these circumstances,
It is an object of the present invention to provide a vehicle that can increase the torsional rigidity while reducing the weight of the rear arm.

In order to achieve this object, the present invention includes one rear arm whose front end is pivotally connected to the vehicle body frame so as to be movable up and down.
In a vehicle in which an axle to which a pair of left and right rear wheels are attached is held at the rear end of the rear arm, the rear arm includes a front pipe that is pivoted to the body frame, a rear pipe that holds the axle, and a front pipe that holds the axle. and a connecting part for connecting the rear pipes, the connecting part is formed in a substantially box shape by a plurality of connecting plates whose front and rear ends are welded to the front and rear pipes, respectively, and the connecting part has a plurality of connecting plates arranged vertically in the vertical direction. It is constructed so that a hollow portion that bulges out is formed.

The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a sectional view taken along line 11 in FIG. 1 of an embodiment in which the present invention is applied to a tricycle. Number 1 in Figure 1.2
0 is the vehicle body frame, which includes a steering head pipe 12, a main pipe 14, a pair of left and right down tubes 16 (16a, 16b), a seat pillar tube 18 (18a, 18b), and a seat rail 20 (20
a, 20b) and back y, chi 22 (22a, 2
2b). , down tube 16
and seat pillar tube 18 are integrally formed by a single pipe, and a pair of left and right brackets are provided at the rear ends of these.
24 (24a.

24b) is welded. This plug) 24a.

24b, the front end of a rear arm 36, which will be described later, is pivotally attached to the pivot shaft 26 so as to be vertically swingable. Reference numeral 28 denotes an engine, which is mounted in a space surrounded by the main pipe 14, down tube 16, and seat pillar tube 18. In FIG. 1, 30 is a front fork, 32 is a front wheel equipped with ultra-low pressure tires, and 34 is a handlebar.

36 is a rear arm. The rear arm 36 is the front pipe 3
8, a rear pipe 40, and a connecting portion 42 that connects these two pipes 38, 40. The connecting portion 42 includes a lower connecting plate 44 and an upper connecting plate 46. The front and rear ends of these connecting plates 44 and 46 are welded to the front pipe 38 and the rear pipe 40, respectively, and the connecting plates 44 and 46 are welded to the front pipe 38 and the rear pipe 40, respectively. .4
Both the left and right sides of 6 are welded together. As a result, the connecting portion 42 is formed into a substantially box shape. Note that the upper connecting plate 46 is
As is clear from FIG. 1.3, the vicinity of the center bulges upward, and as a result, a hollow portion 48 is formed within the connecting portion 42 that bulges in the vertical direction. A bracket 50 is welded near the center of the upper connecting plate 46. As described above, the front pipe 38 is pivotally attached to the vehicle body frame 10 by the pivot shaft 26 so as to be able to swing up and down. The rear pipe 40 has an axle 5
2 is rotatably held. At both ends of this axle 52, a pair of left and right rear wheels 54 (54a
, 54b) are fixed. Further, a sprocket 56 is fixed to this axle 52, and this sprocket 56 and
A chain 60 is wound around the sprocket 58 of the engine 28. Reference numeral 62 designates a cushion unit, the front end of which is pivoted to a bracket 64 fixed to the lower surface of the main pipe 14, and the rear end thereof to a bracket 50 (biaxially layered) fixed to the rear arm 36.

In FIG. 1, 66 is a rear fender, 68 is a seat, and 70 is a fuel tank.

Next, the operation of this embodiment will be explained. The output of the engine 28 is sprocket 58, chain 60, sprocket 56
and is transmitted to the left and right rear wheels 54 via the axle 52, and both rear wheels 54 rotate at the same speed. Impacts caused by unevenness on the road surface are first absorbed by the tires of the rear wheels 54. Shocks that cannot be absorbed by the tires alone are absorbed by the vertical movement of the rear wheels 54, the swinging of the rear arm 36, and the expansion and contraction of the cushion unit 62. At this time, the left and right wheels 54 move up and down as one. When a large impact is applied to only one of the rear wheels 54, a large torsional stress is applied to the rear arm 36. However, since the connecting portion 42 of the rear arm 36 is formed into a substantially box-like shape by connecting plates 44 and 46, and furthermore, the hollow portion 48 inside thereof bulges in the vertical direction, the torsional rigidity is extremely low. Therefore, the rear arm 36 hardly twists, improving steering stability. Further, since the connecting portion 42 is formed by welding the plates 44 and 46, the increase in weight thereof can be suppressed to a minimum. Therefore, the substantial unsprung weight of the rear wheel suspension system is also reduced, and the ground contact of the rear wheels 54 is improved. When making 4 turns,
The driver shifts his weight to cause the inner rear wheel 54 in the turning direction to slide against the road surface. At this time, since the rear arm 36 has high torsional rigidity, each rear wheel 54a, 54b is
The load distribution can be controlled accurately, improving turning performance.

In the above embodiment, the connecting portion 42 is connected to a pair of upper and lower connecting plates 44.
．． 46, but it may be constructed with three or more connecting plates. Furthermore, the rigidity of the rear arm can be further improved by forming grooves bent into an uneven shape as appropriate on the connecting plate. Furthermore, the rear arm can be made even lighter by forming an appropriate opening in the connecting plate at a position that does not adversely affect the rigidity.

It goes without saying that the present invention can also be applied to a four-wheeled vehicle or a vehicle equipped with a differential device between the left and right axles that support the rear wheels.

As described above, in this invention, the connecting portion of the rear arm is formed into a substantially box shape with a plurality of connecting plates, and the hollow portion within the connecting portion is bulged up and down, thereby improving the torsional rigidity and reducing the weight of the rear arm at the same time. be able to.

[Brief explanation of the drawing]

Fig. 1 is a side view showing one embodiment of the present invention, Fig. 2 is a partially omitted plan view, and Fig. 3 is a diagram showing ■-■ in Fig. 1.
FIG. IO...Vehicle frame, 36...Rear arm, 38
...Front pipe, 40... Rear pipe, 42... Connecting part, 44.46... Connecting plate, 48... Hollow part, 52
... Axle, 54... Rear wheel. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] In a vehicle that includes one rear arm whose front end is vertically movably pivoted to the vehicle body frame, and in which an axle to which a pair of left and right rear wheels are attached is held at the rear end of the rear arm, the rear arm is attached to the vehicle body frame. The vehicle includes a front pipe that is attached to the shaft, a rear pipe that holds the axle, and a connecting part that connects these front and rear pipes, and the front and rear ends of the connecting part are welded to the front and rear pipes, respectively. 1. A vehicle, characterized in that it is formed into a substantially box shape by a plurality of connecting plates, and a hollow portion that bulges in the vertical direction is formed in the connecting portion.