JPH0224397Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the structure of the pivot part of the rear fork of a motorcycle, which is improved so that the rear fork and the pivot boss can be welded together with a sufficient welding length so that they can be connected with high rigidity.

On motorcycles, the front parts of the left and right rear forks are connected by a bridge piece, and pivot bosses are welded to the front ends of the left and right rear forks. Then, attach the support shaft passed through the pivot boss to the bracket of the vehicle body, place a cushion unit between the rear fork and the vehicle body, and attach the rear wheel axle to the rear ends of the left and right rear forks. The rear fork swings to allow the rear wheels to lock. Generally, the pivot boss is provided with a protrusion on its side surface, which is inserted into the front end of the rear fork, and the mating surfaces are welded to integrally connect the pivot boss to the rear fork. In this welded part, large bending and torsional stress is generated by the cushion, and if only the surrounding mating surfaces are welded, the weld length is insufficient and sufficient strength cannot be obtained, resulting in insufficient rigidity. Therefore, a reinforcing plate is attached to the outside and welded, but this method is troublesome and expensive, and it also increases the weight.

In view of these points, this invention has been improved so that sufficient strength and rigidity of the welded portion can be obtained, and an embodiment of the invention shown in the drawings will be described below.

The rear hawks 1 are made of a pipe with a rectangular cross section, and there are a pair of left and right rear hawks 1, and these left and right rear hawks 1 are connected to each other by welding a bridge piece 2 at their front parts. Pivot bosses 3 are welded 4 to the front ends of the left and right rear forks 1. The pivot boss 3 is integrally provided with a rib 5 having a cross-shaped cross section and having a protrusion on one side and protruding in the vertical and horizontal directions. At the front end of the rear fork 1, slits 6 are provided on the upper, lower, left and right surfaces. Then, the rib 5 of the pivot boss 3 is fitted into the slit 6, and welded 4 along the rib 5. A support shaft 7 is passed through the left and right pivot bosses 3, and the support shaft is fastened to a bracket 8 of the vehicle body, so that the rear fork 1 is swingably attached. A cushion unit 9 is installed between the rear fork 1 and the vehicle body, and a rear wheel axle 10 is attached to the rear end of the rear fork 1.

The effect will be explained.

The ribs 5 protruding from the top and bottom and left and right surfaces of one side of the pivot boss 3 are fitted into the slits 6 provided on the top and bottom and left and right surfaces of the front end of the rear fork 1. 1. Since the mating surface of the front end is welded 4, the part that goes around the rib 5,
The length of the weld line becomes longer, and the weld 4 becomes stronger. In this way, rigidity is increased, damage can be prevented, twisting of the left and right rear forks 1 is eliminated, and steering stability can be improved.

As explained above, in this invention, the side surfaces of the pivot boss are aligned and welded to the front ends of the left and right rear forks, and a rib having a cross-shaped cross section that protrudes vertically and horizontally is integrally provided on the side surface of the pivot boss. , slits are provided on the top and bottom and left and right sides of the front ends of the left and right rear forks, the ribs of the pivot boss are fitted into the slits, and the welding is done along the ribs, so the welding length is long despite the simple structure. As a result, the welding strength is increased and a box structure is formed in which ribs having a cross-section are formed inside the box shape, so that the rigidity against twisting, bending, etc. can be increased and damage can be prevented. In addition, as the rigidity increases, twisting of the left and right rear forks is eliminated, and steering stability is improved. Moreover, compared to using a reinforcing plate, it is lightweight and can be manufactured at low cost.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, in which Fig. 1 is a side view, Fig. 2 is a plan view with one side omitted, Fig. 3 is an enlarged view of the part indicated by arrow A in Fig. 1, and Fig. 4 is a second It is an enlarged view of the part indicated by the arrow in Figure B. 1... Back Hawk, 3... Pivot Boss, 4...
Welding, 5...rib, 6...slit.

Claims (1)

[Scope of utility model registration request] In the case where the side surfaces of the pivot boss are welded together to the front ends of the left and right rear forks, ribs with a cross-section shaped like a cross are integrally provided on the side surfaces of the pivot boss and project in the vertical and horizontal directions. A pivot part structure of a rear fork of a motorcycle, characterized in that a slit is provided on the left and right surfaces, a rib of a pivot boss is fitted into the slit, and the pivot boss is welded along the rib.