JPS6024885Y2 - Piston pin oil supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for supplying oil to a piston pin of an internal combustion engine.

The piston pin of an internal combustion engine serves to connect the connecting rod to the piston, and since large forces are exerted between the piston and the piston pin during operation, it is necessary to ensure that good lubrication conditions are maintained.

In particular, the upper part of the sliding surface between the piston and piston pin is subject to a large pressure due to the explosion pressure and the sliding speed is slow, making it difficult for an oil film to form, and furthermore, the temperature becomes high, causing poor lubrication due to lack of oil film.

Conventional lubrication methods rely on oil splash from the rotation of the crankshaft or oil jets from the connecting rod, so it is difficult to sufficiently distribute the lubricating oil to the sliding surface at the top of the piston pin by simply splashing it. It was difficult.

In order to change from a basic engine to an engine with a larger displacement, it is often done to increase only the cylinder bore diameter without changing the piston pin, but in this case an extremely large force is applied to the piston pin, so The oil film will break and cause poor lubrication.

An object of the present invention is to provide a piston pin oil supply device that can reliably maintain an oil film between a piston pin and a piston pin boss hole.

In the present invention, the piston pin is fixed to the connecting rod, but is rotatable relative to the piston pin boss hole of the piston pin, which is a so-called semi-float type.

The prerequisite configuration is a ring-type piston support system.

That is, in this system, there is always a one-to-one correspondence between the position of the piston pin and the position of the crankshaft.

Therefore, the relative position of the piston pin and the piston pin bore hole is uniquely determined once the position of the crankshaft is determined.

According to the present invention, in such a floating type piston support system, an oil supply groove is formed on the piston pin so as to pass through an upper position on the piston-crankshaft center line during one engine cycle, and A piston pin oil supply device is provided in which a through oil supply hole is formed in the boss portion to meet the oil supply groove during one cycle of the engine.

According to the configuration of the present invention, the oil supply groove on the piston pin and the oil supply hole in the piston pin boss meet during the downward movement of the piston during the suction stroke and the expansion stroke, so that oil is stored in the oil supply groove.

The oil supply groove is formed at a position where it can reach a position above the piston-crankshaft center line during one engine cycle.

Therefore, the oil supplied to the oil supply groove is subjected to a compression process,
During the exhaust process, the sliding surface between the upper piston pin and the piston pin boss hole, which is subjected to force, can be lubricated.

Referring to the drawings, a piston 10 is fitted into a cylinder bore 12 so as to be vertically slidable.

The piston 10 is formed with a pair of piston pin bosses 14, into which a piston pin 16 is rotatably fitted.

The connecting rod 18 is fixed to the piston pin 16 at its upper end, and connected to the crank pin 17 (its rotation circle is indicated by 1) at its lower end.

The piston pin 16 has a V-shaped groove 2G that is slightly shorter than the fitting length with the boss 14, and the piston pin boss portion 14 is provided with an oil supply hole 22 that meets the groove 20 within a predetermined crank angle range. ing.

The positional relationship between the V-shaped oil supply groove 20 and the oil supply hole 22 is as follows.

That is, it is formed so that it can always pass through at least an upper position on the piston-crankshaft center line m-m during one engine cycle.

Preferably, when the piston 10 is at the top dead center, as shown in FIG. (in the opposite direction to f) by an angle a, which will be described later.

Further, it is preferable that the V-shaped groove 20 and the hole 22 meet when the crank pin 17 rotates by an angle θ, which will be described later, from the top dead center, as shown in FIG.

To describe the operation of the present invention, when the piston 10 is at the top dead center position in FIG. 3 at the start of the suction stroke, the V-shaped groove 2
and the oil supply hole 14 do not meet.

After the crankshaft rotates at an angle of θ, the V-shaped groove 20 and the oil supply hole 14
meet as shown in Figure 4.

During the suction stroke, negative pressure acts on the piston, and the piston's inertia tends to lift the piston 10 upwards.On the other hand, there is sliding resistance between the piston 10 and the cylinder bore 12, so a groove 20 is formed. The clearance between the piston pin 16 and the piston pin boss 14 on the opposite side is larger than that on the opposite side.

As a result, the lubricating oil in the crankcase can be stored in this clearance due to the meeting of the groove 20 and the hole 22.

This stored lubricating oil is supplied to the friction surface between the piston pin 16 and the piston pin boss hole 14 in the next compression stroke.

The groove 20 is positioned so that it can pass through an upper position on the piston-crankshaft center line mm during one cycle of the engine.

Therefore, the oil stored in the groove 20 can be supplied between the upper piston pin 16, which is subject to force, and the piston pin boss hole.

The initial eccentric angle a of the character-shaped groove 20 is determined by the following inequality % formula % (1
) r: crankpin rotation radius 1: preferably within the range of the distance between the connecting rod centers.

The reason for setting a > 5° here is to prevent the corner of the V-shaped groove from being on top of the top during the explosion, where the most force is applied.
This prevents damage to the sliding surface due to breakage of the oil film due to increased local surface pressure at the corners of the groove.

Also, the maximum value φmax (fifth
If the eccentric angle a of the V-shaped groove is not small, the groove 20
cannot come to the upper position on the piston-crankshaft center line m-m, and the sliding surfaces of the upper piston pin and piston pin boss hole, which are subject to force, cannot be lubricated, and the purpose of the present invention cannot be remotely achieved. .

Therefore, a〈φmax=sin−”Φ The above conditions are required.

Next, the crank angle θ (FIG. 4) where the V-shaped groove 20 and the oil supply hole 22 meet is desirably about 2O2.

That is, since the explosion pressure reaches its maximum at a crank angle of about 15 degrees after top dead center, the purpose is to escape this pressure and then bring the groove 20 and the hole 22 together as soon as possible.

Also, the diameter d of the oil supply hole 22 is determined by the following inequality: %formula%) It is necessary to be within the range of .

Here, D is the diameter of the piston pin.

The reason why d<5 mm is set is that if the hole diameter is larger than this, the area of the hole becomes large relative to the pressure-receiving area of the piston pin boss portion, causing a problem of oil film shortage.

In addition, the left side of the above-mentioned inequality indicates that the hole 22 has a swing angle of φ (the fourth
The groove 20 and the hole 22 begin to meet at the center line rn −
This is obtained from the condition that the dimension of the hole 22 such that the groove 20 and the hole 22 finish meeting at the maximum swing angle φmax toward the anti-thrust side from m is the minimum dimension for oil supply.

That is, in FIG. 6, the groove 20 meets the hole 22 at an angle ^i between the elbows and L.

On the other hand, the maximum swing angle φmax is.

When the angle φ is reached, the groove 20 and the hole 22 begin to meet, and φmax
If the groove 20 and the hole 22, which have moved to the position 20', end to meet, the diameter d of the hole 22 is the distance that the groove 20 moves in the circumferential direction between φ and φmax.

Therefore, if D is the diameter of the piston pin and θ=20°, then This is the left-hand side of the above inequality.

As described above, according to the present invention, in the piston pin structure in which the piston pin is fixed to the connecting rod, the piston pin is supplied with oil R20, while the piston pin boss is provided with the oil supply hole 22.
is provided, and the oil supply groove is located along the center line m-m during one engine cycle.
The piston pin 16 is positioned so that it always passes through the upper position, and thereby the sliding surface between the upper piston pin 16, which is subjected to force, and the piston pin boss hole can be lubricated, and good lubrication can be performed without running out of the oil film.

As in the example, the refueling groove and the refueling hole meet when they have turned from top dead center at an angle that is slightly larger than the angle at which the maximum explosion pressure is obtained. Oil supply to the groove 20 can be started from 22, and efficient oil supply can be performed.

In addition, as in the example, the position of the oil supply groove is slightly shifted from the top dead center position to the thrust side, so that the oil supply groove does not come to the top during an explosion where the most force is applied, and the oil film formed by the corner of the oil supply groove Cutting and damage to the sliding surface are prevented.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the fitting part between the piston and piston pin in the present invention, Fig. 2- is a cross-sectional view taken along the line ■-■ in Fig. 1, and Figs. 3, 4, and 5 are respectively FIG. 6 is a diagram illustrating the positional relationship between the V-shaped groove and the oil supply hole at each swing angle of the connecting rod, and FIG. 6 is a diagram illustrating calculation of the diameter of the oil supply hole. 14... Piston pin boss, 16...
Piston pin, 20... Oil supply groove, 22...
...Oil supply hole.

Claims (1)

[Claims for Utility Model Registration] 1. In an internal combustion engine in which a piston pin fixed to a connecting rod from a crank pin is rotatably fitted to a piston pin boss portion of the piston, the piston is placed on the piston pin during one cycle of the engine. A piston pin oil supply device in which an oil supply rod is formed so as to pass through an upper position on the crankshaft center line m-m, and a through oil supply hole is bored in the piston pin boss portion to meet the above oil supply groove during one cycle of the engine. . 2 The oil supply hole is connected to the crankshaft when the piston is at top dead center.
The piston oil supply device according to claim 1, which is slightly shifted toward the thrust side from the piston center line m-m. 3. The oil supply hole and the oil supply groove meet when the crankshaft rotates from top dead center toward the anti-thrust side at an angle that is slightly larger than the angle at which the maximum explosion pressure is obtained.
The piston oil supply device according to item 5.