JPH06212931A - Oil feeder for two-cycle engine - Google Patents

Abstract

PURPOSE:To solve a shortage of oil supply near a small end bearing by providing a piston pin provided with an oil supply path having one end communicating to a crank chamber and the other end opened to small end bearing on the side opposite to the crank chamber. CONSTITUTION:A piston pin 60 is inserted into a piston pin hole 47 of a piston 40. The smaller end 72 of connecting rod 70 on the piston 40 side is supported through a smaller end bearing 74 consisting of a needle bearing on the piston pin 60. Oil enters a crank chamber 14 in response to the reciprocation of the piston 40 and reaches together with fuel directly from a communicating path 53 in the underside of a boss through a spiral groove 64 to a smaller end bearing 74. Also oil in a crank chamber 14 reaches directly the small end bearing 74 through a notch 57. Further, the oil riding on a scavenging flow in a main scavenging path 22 reaches a recess 49 and the smaller end bearing 74 through a communicating hole 51 at the upper part of the boss and a spiral groove 64. Thus, by providing an oil supply path in in the piston pin, the mechanical strength of the smaller end of the connecting rod is prevented from degradation and oil is supplied through an oil supply path to the smaller end bearing near the side opposite to the crank chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil supply device for a two-stroke engine, and more particularly to an oil supply device for supplying oil to a small end bearing arranged in a connecting rod small end.

[0002]

2. Description of the Prior Art Small end bearings are where the load is high and therefore where they must supply more oil than other parts. As a means for supplying oil to this portion, there is one in which a small hole is formed in the small end of the connecting rod in a direction orthogonal to the axis of the piston pin. This small hole is not formed on the entire circumference, but only on the crank chamber side, that is, on the side opposite to the combustion chamber, and conventionally the oil in the crank chamber is supplied to the small end bearing through this small hole.

[0003]

By the way, the installation of the small holes causes a decrease in the mechanical strength of the small end of the connecting rod, so that the arrangement of the small holes is naturally restricted. In particular, it was difficult to dispose on the anti-crank chamber side, that is, the combustion chamber side. As a result, the small-end bearing near the anti-crank chamber side tends to have insufficient oil supply.

[0004] In addition, in marine engines such as outboard motors, there are increasing demands for stricter exhaust gas regulations and fuel saving, the air-fuel ratio tends to be thin, and cooling by fuel is expected to be thin. Moreover, since the oil supply amount is also decreasing, the oil supply shortage is becoming serious.

The present invention has been made in view of the above circumstances, and an object thereof is to supply oil to a small-end bearing, particularly a small-end bearing near the side opposite to the crank chamber, without deteriorating the mechanical strength of the small end of the connecting rod. It is to solve the shortage.

[0006]

In order to achieve the above object, the present invention provides a piston pin with an oil supply passage having one end communicating with the crank chamber, and the other end of the oil supply passage on the side opposite to the crank chamber. By opening to the small end bearing, the oil in the crank chamber is supplied to the small end bearing on the side opposite to the crank chamber through the oil supply passage.

[0007]

The oil in the crank chamber is supplied to the small end bearing, especially the small end bearing in the counter crank chamber, through the oil supply passage provided in the piston pin. This oil particularly contributes to lubrication of the small end bearing on the side opposite to the crank chamber.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a central longitudinal sectional view of a main part of a two-cycle engine for an outboard motor to which the present invention is applied. FIG. 2 is a central longitudinal sectional view of the piston pin alone shown in FIG. Figure 3
[FIG. 2] is a front view of the piston pin alone shown in FIG. 1. FIG. 4 is a central longitudinal cross-sectional view of a main part corresponding to FIG. 1 according to the second embodiment. FIG. 5 is a central vertical cross-sectional view of the piston pin alone shown in FIG. FIG. 6 is a front view of the piston pin alone shown in FIG. FIG. 7 is a front view of a single piston pin according to the third embodiment. 8 is a sectional view taken along line VIII-VIII of FIG. 7. FIG. 9 is a central longitudinal cross-sectional view of the main parts corresponding to FIG. 1 according to the fourth embodiment. FIG. 10 is an external view of the single piston viewed from the X direction in FIG. 9. FIG. 11 is a development view of the cylinder sleeve and the piston pin 60 and the piston communication hole 5
5 is a schematic diagram showing the positional relationship with the piston 5, and shows the respective positional relationships when the piston is at top dead center and bottom dead center.

Reference numeral 10 is a cylinder, 12 is a sleeve press-fitted into the cylinder 10, 40 is a piston that reciprocates in the cylinder 10, 60 is a piston pin, 70 is a connecting rod that connects a crankshaft (not shown) and the piston 40, 20 Is the scavenging passage. 14 is a crank chamber, and this crank chamber 1
4 is defined by a cylinder 10, a piston 40, and a crank case (not shown), and the volume thereof is changed by the reciprocating movement of the piston 40. Reference numeral 16 denotes a combustion chamber, which is defined by the cylinder 10, the piston 40, and a cylinder head (not shown), and the volume thereof is changed by the reciprocating movement of the piston 40.

As shown in FIG. 1, the scavenging passage 20 includes two pairs of main scavenging passages 22, 22 and one auxiliary scavenging passage 24.
(See FIG. 11), the main scavenging passage 22 is shown in FIG.
As shown in FIG. 5, the main scavenging hole 22a opened in the cylinder 10 and the main scavenging passage inlet 22b communicate with the combustion chamber 16 and the crank chamber 14, respectively, and the piston 40 reciprocates to control opening and closing. Similarly, the auxiliary scavenging passage 24 also communicates with the combustion chamber 16 and the crank chamber 14 through the auxiliary scavenging hole 24a opening in the cylinder 10 and the auxiliary scavenging passage inlet 24b, and is controlled to be opened and closed by the reciprocating movement of the piston.

In the cylinder 10, the main scavenging holes 22a,
In addition to the auxiliary scavenging hole 24b, the exhaust hole 26 is opened at a position sandwiched by the pair of main scavenging holes 22a and at a position facing the auxiliary scavenging hole 24b, and the opening / closing is controlled by the reciprocating movement of the piston.

As shown in FIG. 1, the piston 40 includes a combustion chamber 1
6 and a piston skirt 44 continuous with the piston crown 42, and a pin boss 46 for supporting the piston pin 60 is formed in the piston skirt 44. The pin boss 46 has a piston pin hole 47. And a cylindrical piston pin 60 is inserted into the piston pin hole 47. The pin boss 46
A recess 49 is formed between the piston skirt 44 in the vicinity and the cylinder 10.

The pin boss 46 has a boss lower communication hole 53 which communicates the outer peripheral surface 62 of the piston pin 60 with the crank chamber 14, and a boss upper communication hole 51 which communicates the outer peripheral surface 62 with the recess 49. Penetrates.

A connecting rod small end 72 of the connecting rod 70 on the piston 40 side is pivotally supported on the piston pin 60 via a small end bearing 74 made of a needle bearing. Side washers 76 are mounted between both side surfaces of the connecting rod small end 72 and the inner surface of the pin boss 46. In addition,
A notch 57 is formed on the inner surface of the pin boss 46 on the crank chamber 14 side.
Is formed so that the oil component in the crank chamber 14 reaches the outer peripheral surface 62 of the piston pin 60.

Next, the oil supply device will be described.

As shown in FIGS. 2 and 3, a set of spiral spiral grooves 64 are formed on the outer peripheral surface 62 of the piston pin 60 in opposite winding directions and extend to both ends of the piston pin 60 to form a piston pin. It ends at a slight interval near the center of 60. The set of spiral grooves 64 is in communication with the boss upper communication hole 51 while being mounted on the piston 40. This causes the small end bearing 74 to communicate with the recess 49. In addition, this pair of spiral grooves 64 is
In the state of being attached to the boss, it communicates with the boss lower communication hole 53. As a result, the small end bearing 74 is moved to the crank chamber 14
Communicate with.

Next, the operation of the first embodiment will be described.

In accordance with the reciprocating movement of the piston 40, the air-fuel mixture is sucked from a carburetor (not shown) and the oil is sucked from an oil pump into the crank chamber 14, where it is pre-compressed and then burned through the scavenging passage 20. It is guided to the chamber 16 and used for combustion.

While the piston 40 reciprocates, the oil component in the crank chamber 14 reaches the small end bearing 74 through the spiral groove 64 from the boss lower communication hole 53 together with the fuel component, and the small end bearing 74. Is used for lubrication. Also,
The oil component in the crank chamber 14 directly reaches the small end bearing 74 through the notch 57 and is used for lubricating the small end bearing 74. Further, the oil component reaches the recess 49 by riding on the scavenging air flow in the main scavenging passage 22, and the oil component reaches the small end bearing 74 through the boss upper communication hole 51 and the spiral groove 64, and the small end bearing 74. Is used for lubrication.

Since the piston pin 60 of the first embodiment is tightly fitted in the piston pin hole 47, the piston pin 60 is prevented from rotating in the piston pin hole 47, but a loose fitting is made between them. If so, the piston pin hole 4
The piston pin 60 comes to rotate within 7. By doing so, the rotation of the piston pin 60 causes the spiral groove 64
The oil attached inside is positively supplied to the small end bearing 74. In addition, the boss upper communication hole 51 and the boss lower communication hole 53 come into contact with not only the spiral groove 64 but also the entire circumference of the outer peripheral surface 62, increasing the chances of the oil component adhering to the small end bearing 74. Increase the supply of.

Even when the piston pin 60 rotates, since the spiral grooves 64 are formed in the opposite winding directions, the thrust forces cancel each other out, and the connecting rod small end 72 is brought closer to one pin boss 46 side. There is no.

Next, a second embodiment will be described with reference to FIGS. Since the structure of the second embodiment is basically the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted.

The second embodiment is different from the first embodiment in that the boss upper communicating hole 51 is formed in the pin boss 46 and the spiral groove 64 is formed.
Is not provided on the piston pin 60, and further, a central wall 66 is formed near the center of the piston pin 60, and two pairs of two pin communication holes 68 are formed to sandwich the central wall 66. That is the point.

Next, the operation of the second embodiment will be described.

In the second embodiment, a pair of upper and lower pin communicating holes 68 replaces the spiral groove 64 and supplies oil to the small end bearing 74. That is, when the main scavenging hole 22 a faces the recess 49 of the piston 40, a part of the scavenging air flows into the recess 49 and collides with the central wall 66 through the hollow portion of the piston pin 60. A part of it reaches the small end bearing 74 through the pin communication hole 68. The oil component contained in the scavenging air flow is guided to the vicinity of the center of the small end bearing 74 through the above route and is used for lubrication of the small end bearing 74. In this case, since the piston pin 60 is firmly fitted in the piston pin hole 47, it does not rotate between them.
Therefore, if the piston pin 60 is fitted into the piston pin hole 47 so that the two sets of pin communication holes 68 are located on the combustion chamber 16 side and the crank chamber 14 side (in the left-right direction in FIG. 4), the piston pin 60 is always counteracted Oil is supplied to the small end bearing 74 on the crank chamber side. Incidentally, as in the first embodiment, the piston pin 6
0 may be rotated. In this case, when the piston pin 60 rotates and one of the pin communication holes 68 faces the side opposite to the crank chamber, the oil supply is performed.

Next, the structure and operation of the third embodiment will be described with reference to FIGS.

The third embodiment is, so to speak, a compromise between the first and second embodiments. That is, the piston pin 60 has a pair of spiral grooves 64 formed on the outer peripheral surface 62, and the center wall 66 and the pin communication hole 68 similar to those of the second embodiment are formed in the inner center.
Are formed. In addition, a boss upper communication hole 51 similar to that of the first embodiment is formed in the pin boss 46 to connect the recess 9 and the spiral groove 64.

In the third embodiment, the oil component entered in the recess 49 collides with the central wall 66 through the center of the piston pin 60, passes through the pin communicating hole 68, and the small end bearing 74.
Reach near the center of. On the other hand, the oil in the recess 49 reaches the small end bearing 74 through the boss upper communication hole 51 and the spiral groove 64. The oil component contributes to the lubrication of the small end bearing 74, especially the small end bearing on the side opposite to the crank chamber, from both routes.

Next, the structure and operation of the fourth embodiment will be described with reference to FIGS.

The fourth embodiment is substantially the same as the first embodiment, and the same reference numerals are given and the description thereof is omitted. The different point of the fourth embodiment is that a pair of two piston communication holes 55 that communicate between the recess 49 and the inside of the piston 40, which is the back side of the piston crown 42, are formed in both sides of the piston 40. . As shown in FIG. 11, when the recess 49 looks into the main scavenging hole 22a, the head of the scavenging air enters the recess 49, and a part of the scavenging air passes through the piston communicating hole 55 and hits the back side of the piston crown 42. Piston 40
Reach inside. Since the small end bearing 74 on the side opposite to the crank chamber is located in the vicinity thereof, it contributes to lubrication of that portion. That is, both sides of the connecting rod small end 72 and the pin boss 46.
Since there is a slight gap between the inner surface of the piston and the inner surface of the piston, the oil that sneaks into the back side of the piston crown 42 through the gap reaches the small end bearing 74 and is used for lubrication.

In this embodiment, the central wall 66 and the pin communicating hole 6 provided on the piston pin 60 serve as an oil supply passage.
8 or the example of the spiral groove 64 provided in the piston pin 60 and the boss upper communication hole 51 provided in the pin boss 46 is shown, but the present invention is not limited to this, and various grooves or holes may be provided in the piston pin. Needless to say, the oil supply passage can be configured, and the shape and structure are not limited to those shown in the drawings.

[0032]

According to the present invention, since the oil supply passage is provided in the piston pin, the mechanical strength of the connecting rod small end is not deteriorated, and the oil supply passage is provided in the small end bearing near the side opposite to the crank chamber. The oil is supplied via this, and there is an effect that the shortage of the oil supply in the vicinity can be eliminated.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention, FIGS. 4 to 6 show a second embodiment of the present invention, FIGS. 7 and 8 show a third embodiment of the present invention, and FIGS. 4A and 4B are drawings showing a fourth embodiment of the present invention.

FIG. 1 is a central longitudinal sectional view of a main part of a two-cycle engine for an outboard motor to which the present invention is applied.

FIG. 2 is a central vertical cross-sectional view of the piston pin alone shown in FIG.

FIG. 3 is a front view of a single piston pin shown in FIG.

FIG. 4 is a central longitudinal cross-sectional view of a main part corresponding to FIG. 1 according to a second embodiment.

5 is a central vertical cross-sectional view of the piston pin alone shown in FIG.

6 is a front view of the single piston pin shown in FIG. 4. FIG.

FIG. 7 is a front view of a single piston pin according to a third embodiment.

8 is a sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a central longitudinal cross-sectional view of a main part corresponding to FIG. 1 according to a fourth example.

10 is an external view of the piston alone as seen from the X direction in FIG. 9.

FIG. 11 is a development view of a cylinder sleeve and a piston pin 6
0 and the piston communication hole 55 are schematic diagrams showing the positional relationship between the piston at the top dead center and the bottom dead center.

[Explanation of symbols]

 10 ... Cylinder 12 ... Cylinder sleeve 14 ... Crank chamber 16 ... Combustion chamber 22 ... Main scavenging passage 40 ... Piston 46 ... ... Pin boss 49 ... Recess 51 ... Boss upper communication hole 55 ... Piston communication hole 60 ... Piston pin 62 ... Outer peripheral surface 64 ...・ ・ ・ Spiral groove 66 ・ ・ ・ ・ ・ Central wall 68 ・ ・ ・ ・ ・ Pin communication hole 70 ・ ・ ・ ・ ・ Connecting rod 72 ・ ・ ・ Connecting rod small end 74 ・ ・ ・ ・ ・ Small end bearing

Claims (1)

[Claims] 1. An oil supply passage having one end communicating with a crank chamber is provided in a piston pin, and the other end of the oil supply passage is opened to a small end bearing on the side opposite to the crank chamber, whereby the oil in the crank chamber is replaced with the oil. An oil supply device for a two-cycle engine configured to be supplied to the small end bearing on the side opposite to the crank chamber via a supply passage.