JPS6126565Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement in the lubrication structure of a piston pin.

(Prior Art) Generally, in a reciprocating piston engine, the piston and connecting rod are connected via a piston pin, and the piston pin is rotatably attached to a piston pin boss bored in the piston. It is necessary to lubricate the space between the piston pin boss and the piston pin with oil to prevent seizure and wear.

Therefore, in the past, an oil passage was provided in the axial direction of the piston pin boss that communicated between the back surface of the oil ring groove and the inner circumferential surface of the piston pin boss, and the oil passage actively channeled the oil accumulated in the oil ring groove to the inner circumferential surface of the piston pin boss. Something that guides and lubricates it has been proposed.

However, since the explosion pressure received at the top of the piston is concentrated near the piston pin boss, providing an oil passage above the piston pin boss results in a significant decrease in the strength near the piston pin boss, which poses the problem of deteriorating the durability of the piston. be.

Therefore, the oil passages that communicate the oil ring groove and the inner peripheral surface of the piston pin boss are made substantially perpendicular to the axial direction of the piston pin boss, and two oil passages are provided on each side symmetrically with respect to the axial direction of the piston pin boss. For example, one that is shifted with respect to the axial direction of the pin boss is disclosed in Japanese Utility Model Application Publication No. 55-4315.

However, in the above model, since the oil passage is also formed on the exhaust side, the wall thickness of the piston pin boss part is thinner, and as a result, the thin wall part is subjected to thermal effects in addition to explosion pressure, causing cracks in the piston. There is a problem that occurs.

(Purpose of the invention) The present invention was made in view of the conventional problems, and the purpose is to provide a piston pin lubrication structure that can lubricate between the piston pin and the piston pin boss without reducing the strength of the piston. shall be.

(Structure of the invention) In order to achieve the above object, the present invention is characterized by the following structure.

In other words, by providing the oil passage from the oil ring groove with a predetermined angle of inclination only toward the intake side with respect to the axial direction of the piston pin boss, the distance between the piston pin and the piston pin boss can be positively improved without reducing the strength of the piston. It is designed to lubricate the

(Examples) Hereinafter, the present invention will be specifically explained based on examples.

As shown in FIGS. 1 and 2, a connecting rod 3 is connected to the piston 1 via a piston pin 2. As shown in FIGS. The piston pin 2 is rotatably attached to a piston pin boss 4 bored in the piston 1. Further, one end of an oil passage 6 through which oil for lubricating the inner circumferential surface 5 passes is opened in the inner circumferential surface 5 of the piston pin boss 4 . The other end of the oil passage 6 opens into a back surface 8 of the oil ring groove 7. Above oil passage 6
is composed of a passage 9 perpendicular to the piston pin boss 4 and a passage 10 horizontally, and the horizontal passage 10 is located only on the intake side with respect to the axial direction of the piston pin boss 4, that is, on the combustion chamber (Fig. It is inclined at a predetermined angle in the direction in which the intake valve 14 (not shown) is located.

Note that 11 is a pressure ring for keeping the combustion chamber of the engine airtight, 12 is an oil ring for scraping oil from the surface of the cylinder liner 13 downward, and 15 is an exhaust valve.

If the piston pin lubrication structure is configured as described above, when the piston 1 descends, the cylinder liner 1
The oil on the surface of the oil ring 3 is scraped off by the oil ring 12 and flows into the oil ring groove rear surface 8 through the gap between the oil ring 12 and the oil ring groove 7 below. The oil that has flowed into the oil ring groove back surface 8 is actively supplied to the inner circumferential surface 5 through the oil passage 6, so that good lubrication can be achieved, and the passage 10, which is a part of the oil passage 6, is actively supplied to the inner circumferential surface 5. By inclining the piston 1 at a predetermined angle with respect to the axial direction, the influence of the explosion pressure received at the top of the piston 1 on the oil passage 6 is reduced compared to the conventional piston 1, so that the durability of the piston 1 is improved. Furthermore, the oil passage 6 is inclined toward the intake side where the temperature is relatively low within the piston 1, which is more preferable in terms of the durability of the piston 1.

In the above embodiment, the passage 9, which is a part of the oil passage 6 that opens to the piston pin boss 4, is provided perpendicularly to the axial direction of the piston pin boss 4.
It is okay to have a slope. Further, the passage 10 which is a part of the oil passage 6 also has an oil ring groove 7.
The oil ring groove 7 does not need to be opened on the back side 8 of the
It may be opened on the bottom surface.

(Effects of the invention) As explained above, according to the invention, by inclining the oil passage provided from the oil ring groove at a predetermined angle only toward the intake side with respect to the axial direction of the piston pin boss, the piston pin and the piston pin boss are Furthermore, since the wall thickness of the piston pin boss on the exhaust side can be ensured without reducing the lubrication between the piston pin and the piston pin, the durability of the piston pin can be improved.

[Brief explanation of the drawing]

Figure 1 is a top view showing an embodiment of the present invention;
The figure is a - sectional view in FIG. 1. 1... Piston, 2... Piston pin, 3...
Connecting rod, 4...Piston pin boss, 5...Inner peripheral surface, 6...Oil passage, 7...Oil ring groove, 14...Intake valve.

Claims (1)

[Scope of utility model registration request] A piston pin that connects the piston and connecting rod is pivotally supported by a piston pin boss bored in the piston, and an oil passage is provided that communicates the inner peripheral surface of the piston pin boss with the oil ring groove. A piston pin lubrication structure in which oil in an oil ring groove is guided to the inner circumferential surface of a piston pin boss, characterized in that the oil passage is inclined at a predetermined angle only toward the intake side with respect to the axial direction of the piston pin boss. Piston pin lubrication structure.