JPS603387Y2 - engine crankshaft - Google Patents

Description

[Detailed description of the invention] This invention is designed to improve cooling and lubrication by facilitating the supply of splash lubricating oil to the large end of the connecting rod (hereinafter referred to as the "rod") of the engine. This relates to improvements aimed at preventing burnout accidents.

Particularly in the case of two-stroke engines that use mixed fuel for lubrication, it is obvious that the difficulty in supplying droplet lubrication has a great deal to do with the frequency of burnouts.

Furthermore, the large end of the rod has a high bearing linear speed, so lubrication and cooling are necessary.

A detailed explanation will be given below using examples.

Fig. 1 shows a side view of the assembly of the crankshaft and piston, Fig. 2 shows a sectional view taken along the arrows in Fig. 1, and Fig. 3 shows a partially enlarged detailed view of Fig. 1. .

The embodiment of the present invention relates to a specific structure for lubricating the big end of a piston, connecting rod, and crank pin of a two-stroke engine.

The piston 1 is connected to the small end 4 of the rod 2 by a piston pin 10.

At this time, the gap between the rod 2 and the side surface of the piston pin boss is regulated (referred to as small end regulation) to limit lateral vibration of the rod 2.

The large end 5 of the rod 2 is fitted with a needle bearing 6 with a cage 13, loosely fitted onto the crank pin 3, and assembled between the crank arms 7.7.

When these are further assembled into the main body crankcase and cylinder, the piston 1, cylinder and rod 2
are each regulated within a dimensional tolerance along with the small end regulation, and the large end 5 of the rod 2 is held at a predetermined position on the crank pin 3, and both sides of the large end 5 are attached to the crank arm 7. A predetermined gap can be maintained with the inner surface of .7.

The outer periphery of the surface facing the cage 13 of the needle bearing 6 on the inner side of the crank arm 7.7 facing the large end of the rod 5 is removed, leaving an annular trapezoidal contact surface 8 around the crank pin 3. The annular trapezoidal contact surface 8 is formed to have a small diameter d relative to the outer diameter of the needle bearing 6.

As a result, in the vicinity of the outer circumference 12 of the needle bearing ring 6, step gaps 9, 9 are formed that are continuous with the gap and widened on the outer circumference side, and at least part of the outer circumference 12 of the needle bearing ring 6 is formed. is exposed and comes into direct contact with the air-fuel mixture in the crank chamber through this peripheral gap, allowing sufficient gas exchange.

As a result of the above, the present invention has the following effects.

By providing the stepped gap as described above, it is possible to provide a gap with a sufficient width near the outer circumference 12 of the needle bearing 6 without impairing the strength of the crankpin base. Due to the vertical movement of the crankshaft, the mixture fuel gas in the crank chamber easily enters and passes through the gap, collides with the needle bearing ring 6, etc., and performs a moist cooling effect on the bearing portion, contributing to lubrication.

In this way, the rod and crankshaft implemented in this invention reduce the lateral pressure load on the large end side by restricting the small end of the rod, improve oil lubrication at the large end as described in detail, aid cooling, and prevent bearing burnout. This contributes to prevention.

[Brief explanation of drawings]

Figure 2: A sectional view taken along arrows 1--2 in Figure 1. Figure 3: A partially enlarged detailed view of Figure 1. 1... Piston, 2... Connecting rod, 3... Crank pin, 4... Small end, 5... Bent large end, 6... ...Needle bearing with cage, 7,7...Crank arm, 8
...Annular trapezoidal contact surface, 9.9...Stepped gap, 12...Needle bearing ring outer periphery.

Claims (1)

[Scope of utility model registration request] In the moving part assembled with the piston 1, connecting rod 2, and crank pin 3 of the engine, the connecting rod 2 is assembled with a small end 4 restriction method, and a caged needle bearing 6 is attached to the large end 5 of the connecting rod.
The outer periphery of the surface of the needle bearing 6 facing the cage 13 on the inside of both crank arms 7.7 is removed to create an annular trapezoidal contact surface 8 having a smaller diameter d than the outer diameter of the needle bearing 6. At least the outer periphery 12 of the needle bearing 6 is provided around the pin 3, and a stepped gap 9.9 is provided between both sides of the large end 5 of the connecting rod 2 and the inner side of the crank arm 7.7. An assembled crankshaft for an engine, characterized in that a part of the crankshaft is exposed so as to be easily lubricated by direct contact with the fuel mixture in the crank chamber.