JP2012132405A - Lubrication structure for piston pin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a suitable lubricating oil film between an inner circumference of a shaft hole of a small end of a connecting rod and an outer circumference of a piston pin.SOLUTION: In a lubrication structure for a piston pin 2 of an all-floating type connecting a connecting rod 1 with a piston 3, the connecting rod 1 is provided with a lubricating oil passage 13 extending toward a small end and in communication with a shaft hole 12 of the small end. An outlet 132 of the oil passage 13 is opened at a part biased along the circumferential direction of the shaft hole 12 from a central axis L of the connecting rod 1. A recess 21 is molded at a part facing the outlet 132 in the outer circumferential surface of the piston pin 2. Accordingly, the piston pin 2 receives an oil pressure of the lubricating oil reaching the shaft hole 12 of the small end through the lubricating oil passage 13 at the recess 21, and is constantly rotated in the shaft hole 12.

Description

  The present invention relates to a lubrication structure for a fully floating piston pin that connects a connecting rod and a piston of an internal combustion engine.

  In an internal combustion engine, the reciprocating motion of a piston is transmitted to a crankshaft via a connecting rod (connecting rod) and output as a rotational driving force. The small end of the connecting rod and the piston are connected by a piston pin. The fully floating piston pin is inserted into the shaft hole at the small end portion of the connecting rod and the pin hole at the boss portion of the piston, and can rotate with respect to the connecting rod and the piston.

  In order for the piston to reciprocate smoothly, the piston pin must be properly lubricated. For this purpose, a lubricating oil passage extending toward the small end portion and communicating with the shaft hole of the small end portion is provided inside the connecting rod. In addition, in what is disclosed in the following patent document, an introduction hole is provided to communicate the outer periphery and the inner periphery of a cylindrical piston pin. Lubricating oil is provided in the interior of the piston pin through the introduction hole. In this way, the shaft end of the piston pin and the boss of the piston are also supplied.

  However, with such a structure, the speed of relative rotation of the piston pin with respect to the shaft hole at the small end is temporarily zero due to the swinging motion of the connecting rod, and the inner periphery of the shaft hole and the outer periphery of the piston pin are In some cases, a lubricating oil film could not be formed well.

JP 2005-127227 A

  An object of the present invention is to make it possible to suitably form a lubricating oil film between the inner periphery of the shaft hole at the small end of the connecting rod and the outer periphery of the piston pin.

  In the present invention, in a lubricating structure of a fully floating type piston pin that connects a connecting rod and a piston of an internal combustion engine, a lubricating oil passage extending toward the small end portion and communicating with the shaft hole of the small end portion is provided in the connecting rod. The outlet of the oil passage is opened at a location deviated from the central axis of the connecting rod along the circumferential direction of the shaft hole, and at the outer peripheral surface of the piston pin inserted into the shaft hole at the small end of the connecting rod and the pin hole of the piston. A recess was formed at the part facing the outlet. Thereby, the piston pin receives the hydraulic pressure of the lubricating oil that has reached the shaft hole at the small end through the lubricating oil passage, and is in a state of constantly rotating in the shaft hole.

  According to the present invention, a lubricating oil film can be suitably formed between the inner periphery of the shaft hole at the small end of the connecting rod and the outer periphery of the piston pin.

The front sectional view showing the lubrication structure of one embodiment of the present invention. The sectional side view of the lubricating structure of the embodiment. The front sectional view showing a modification of the present invention. The front sectional view showing a modification of the present invention.

  An embodiment of the present invention will be described with reference to the drawings. In the lubricating structure of the present embodiment shown in FIGS. 1 and 2, a shaft hole 11 into which a crank pin of a crankshaft (not shown) is inserted is provided at the large end of the connecting rod 1, and a piston pin 2 is provided at the small end. A shaft hole 12 to be inserted exists. A connecting rod bearing 111 is attached to the shaft hole 11 at the large end, and a bush 121 is attached to the shaft hole 12 at the small end.

  Inside the connecting rod 1 is provided a lubricating oil passage 13 for guiding the lubricating oil to the shaft hole 12 at the small end. The lubricating oil passage 13 connects the inside of the large end shaft hole 11 and the inside of the small end shaft hole 12, and the inlet 131 opens to the inner peripheral surface of the large end shaft hole 11, and the outlet 132. Is opened on the inner peripheral surface of the shaft hole 12 at the small end. As shown in FIG. 1, the position of the outlet 132 of the lubricating oil passage 13 is the center axis L of the connecting rod 1, that is, the center of the shaft hole 11 at the large end and the center of the shaft hole 12 at the small end. Is offset from the straight line passing through the circumferential direction of the shaft hole 12.

  The piston pin 2 that connects the small end portion of the connecting rod 1 and the piston 3 so as to be relatively rotatable has a substantially cylindrical shape. On the outer peripheral surface of the intermediate portion facing the outlet 132 of the lubricating oil passage 13, A plurality of recesses 21 are formed intermittently along the circumferential direction.

  The piston 3 includes bosses that are opposed to each other in the front-rear direction, and pin holes 31 penetrating the bosses are provided on the concentric shaft so that the small end portion of the connecting rod 1 fits in the gap between the bosses.

  In connecting the connecting rod 1 and the piston 3, the piston pin 2 is inserted into the shaft hole 12 at the small end portion and the pin hole 31 of the piston 3, and the snap ring 22 is connected to the shaft end of the piston pin 2 from before and after the boss portion. Fit. The snap ring 22 restricts the movement of the piston pin 2 in the axial direction and prevents the piston pin 2 from being pulled out from the shaft hole 12 and the pin hole 31, while the shaft hole 12 and the pin hole of the piston pin 2. Rotation with respect to 31 is allowed.

  The lubricating oil supplied to the shaft hole 11 at the large end of the connecting rod 1 reaches the shaft hole 12 at the small end via the lubricating oil passage 13 inside the connecting rod 1. The hydraulic pressure enters the recess 21 formed in the intermediate portion of the piston pin 2 that is in sliding contact with the outlet 132 of the lubricating oil passage 13, and causes the piston pin 2 to move in a fixed direction (counterclockwise in FIG. 1) with respect to the connecting rod 1 and the piston 3. Rotate to This rotation makes it possible to always lubricate the outer periphery of the piston pin 2. The lubricating oil passage 13 extends substantially straight from the large end shaft hole 11 to the small end shaft hole 12, and can efficiently transmit the lubricating oil pressure to the piston pin 2.

  According to the present embodiment, in the lubricating structure of the all-floating piston pin 2 that connects the connecting rod 1 and the piston 3 of the internal combustion engine, the connecting rod 1 extends toward the small end and extends into the shaft hole 12 at the small end. And an outlet 132 of the oil passage 13 is opened at a location deviated from the central axis L of the connecting rod 1 along the circumferential direction of the shaft hole 12, and the shaft of the small end portion of the connecting rod 1 is provided. Since the concave portion 21 is formed at a portion facing the outlet 132 on the outer peripheral surface of the piston pin 2 inserted into the hole 12 and the pin hole 31 of the piston 3, the piston pin 2 reaches the shaft hole 12 at the small end portion through the lubricating oil passage 13. The oil pressure of the lubricating oil thus received is received by the recess 21, and the lubricating oil is constantly rotated in the shaft hole 12. Accordingly, a lubricating oil film can be suitably formed between the inner periphery of the shaft hole 12 at the small end portion of the connecting rod 1 and the outer periphery of the piston pin 2, reducing the friction between the small end portion and the piston pin 2, and improving fuel efficiency. Can contribute.

  In addition, this invention is not limited to embodiment described in full detail above. For example, in the above embodiment, the recesses 21 are provided intermittently along the outer periphery of the piston pin 2, but the recesses 21 may be provided substantially continuously as shown in FIG. 3.

  In the above embodiment, the lubricating oil passage 13 is extended substantially parallel to the central axis L of the connecting rod 1, but the lubricating oil passage 13 is tilted with respect to the central axis L as shown in FIG. The outlet 132 may be biased from the central axis L.

  Moreover, in the said embodiment, although the lubricating oil path 13 was made into linear form, as shown in FIG. It may be biased.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 1 ... Connecting rod 12 ... Small end shaft hole 13 ... Lubricating oil path 132 ... Outlet 2 ... Piston pin 21 ... Recessed part 3 ... Piston 31 ... Pin hole

Claims (1)

A lubricating structure of a fully floating piston pin that connects a connecting rod and a piston of an internal combustion engine,
The connecting rod is provided with a lubricating oil passage that extends toward the small end and communicates with the shaft hole at the small end, and the outlet of this oil passage is opened at a location that is biased from the central axis of the connecting rod along the circumferential direction of the shaft hole. As well as
A piston pin lubrication structure, wherein a concave portion is formed in a portion facing the outlet in an outer peripheral surface of a piston pin inserted into a shaft hole of a small end portion of a connecting rod and a pin hole of a piston.

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