JP3303076B2 - 2 cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke engine of a scavenging type in a crankcase, and more particularly to a two-stroke engine capable of lubricating around a piston pin connected to its piston.

[0002]

2. Description of the Related Art In a two-stroke cycle engine of a scavenging type in a crankcase, a piston pin for supporting a piston reciprocally provided in a cylinder and a crankshaft supported by a crankcase are connected by a connecting rod, and a crank connected to the cylinder is connected. The chamber is a primary compression chamber of the intake air. Such 2
In a cycle engine, the lubricating oil required for lubrication cannot be stored at the bottom of the crankcase, so the bearings, such as the sliding surface between the cylinder and piston, the journal of the crankshaft, etc. Some direct lubrication systems that supply lubricating oil are used. Further, lubrication around the piston pin connected to the piston is performed by suspending mist-shaped oil in the air-fuel mixture supplied to the crank chamber and attaching the oil mist around the small end of the connecting rod. .

[0003]

However, according to such a structure, since lubricating oil cannot be directly supplied around the piston pin which receives a large explosion pressure, the periphery of the piston pin is worn or seized. A problem such as a cause occurs.

[0004] In order to improve the lubrication conditions around the piston pin, for example, an oil communicating from the deepest portion of the piston ring groove into which the piston ring is fitted to a pin hole into which the piston pin fits or a small end of a connecting rod. It is conceivable that a passage is formed and lubricating oil is guided by the oil passage. By the way, in a two-cycle engine, a large explosion pressure is applied to the piston ring groove. If this explosion pressure escapes to the crank chamber through the oil passage through the piston ring groove, one of the causes of a decrease in engine performance. Become.

[0005] The present invention has been made in view of such circumstances, and provides a two-cycle engine in which lubrication reliability can be improved by directly lubricating around a piston pin without affecting engine performance. It is intended to provide.

[0006]

In order to solve the above-mentioned problems, the present invention relates to connecting a piston pin for supporting a piston reciprocally provided in a cylinder and a crankshaft supported on a crankcase by a connecting rod. In a two-cycle engine in which a crank chamber connected to a cylinder is a primary compression chamber of intake air, one piston pin is fitted at a position below the piston ring of the piston and on a side facing the exhaust passage of the cylinder. An oil sump groove is provided from the pin hole to a position above the other piston pin hole, and lubricating oil is supplied between the cylinder and the piston on the side of the cylinder corresponding to the oil sump groove when the piston is near bottom dead center. Forming an oil supply opening for supply, a pin hole in which the oil sump groove is fitted with the piston pin or the connecting rod; It is characterized in that the formation of the oil passage that guides the lubricating oil communicates with the small end.

[0007]

According to the present invention, as the piston reciprocates in the cylinder, lubricating oil adhering to the cylinder is efficiently collected by the oil reservoir groove provided below the piston ring, and the piston pin is formed by the oil passage. The lubricating oil is guided to the fitted pin hole or the small end of the connecting rod and collected in an oil reservoir groove provided below the piston ring, and the lubricating oil is supplied directly around the piston pin to be lubricated. By providing an oil sump groove from a pin hole in which one piston pin fits on the side opposite to the exhaust passage of the cylinder at a position below the piston ring of the piston and above the other piston pin hole, It is possible to prevent unburned carbon from being deposited in the oil sump groove. In addition, by forming an oil supply opening for supplying lubricating oil between the cylinder and piston on the side of the cylinder corresponding to the oil sump groove when the piston is near the bottom dead center, lubricating oil directly lubricates around the piston pin. Therefore, the circumference of the piston pin can be directly and reliably lubricated without affecting the engine performance, and wear and seizure around the piston pin can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a two-stroke engine according to the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of a two-stroke engine, FIG. 1 is a longitudinal sectional view of the two-stroke engine, FIG. 2 is a sectional view taken along the line II-II in FIG.
Is a cross-sectional view near the bottom dead center of the piston showing the oil supply port of the cylinder block and the oil sump groove of the piston, FIG. 4 is an enlarged view of the bearing at the small end of the connecting rod, and FIG. It is a longitudinal section showing an oil sump groove.

This two-stroke engine has a crankcase 1, which comprises an upper case 2 and a lower case 3. A crankshaft 4 is rotatably supported between the upper case 2 and the lower case 3 via bearings 5 and 6, and the upper case 2 and the lower case 3 form a crank chamber 7. An intake pipe 9 is attached to the upper case 2 via a reed valve 8. The reed valve 8 allows only the flow of the intake air from the intake pipe 9 to the crank chamber 7, and the crank chamber 7 is used as a primary compression chamber of the intake air. And

A cylinder block 10 is mounted on the upper case 2 of the crankcase 1, and a cylinder head 11 is mounted on the cylinder block 10. A piston 13 is provided in the cylinder 12 formed in the cylinder block 10 so as to be able to reciprocate, and a combustion chamber 14 is formed between the cylinder 12 of the cylinder block 10, the head of the piston 13, and the cylinder head 11. An ignition plug 15 is attached to the cylinder head 11 so as to face the combustion chamber 14. The cylinder block 10 has three scavenging passages 16 communicating the crank chamber 7 and the combustion chamber 14 in a scavenging stroke, and an exhaust passage 17 for discharging exhaust gas from the combustion chamber 14 in an exhaust stroke. I have. Two scavenging passages 16 among the three scavenging passages 16 are arranged to face each other in the radial direction of the cylinder 12, and the remaining one scavenging passage 16 is connected to the two scavenging passages 16 facing each other. , And is disposed to face the exhaust passage 17.

Two piston ring grooves 18 are formed in the upper part of the piston 13, and a piston ring 19 is fitted in each of the piston ring grooves 18. The piston 13 has a skirt portion 2 which is in sliding contact with the inner surface of the cylinder 12.
A pair of bosses 21 are formed on the inner surface of the skirt portion 20 so as to face each other in the radial direction of the piston 13. A pin hole 23 through which the piston pin 22 passes is formed in the boss portion 21, and the small end 25 of the connecting rod 24 is located between the boss portions 21. The small end 25 of the connecting rod 24 is connected to the piston pin 22 via a bearing 26.
A large end 27 of the connecting rod 24 is supported by a crank pin 28 of the crankshaft 4 via a bearing 29. The connecting rod 24 converts the reciprocating motion of the piston 13 into a rotating motion, It is transmitted to the shaft 4.

An oil supply opening 30 for supplying lubricating oil is formed in the cylinder block 10, and lubricating oil is supplied between the cylinder 12 and the piston 13 from an oil supply pipe 31 connected to the oil supply opening 30. The oil supply opening 30 is provided at a position where the oil supply opening 30 is closed at the upper portion of the skirt portion 20 of the piston 13 when the piston 13 reaches or near the bottom dead center. For this reason, the lubricating oil guided through the oil supply pipe 31 is supplied to the inner surface of the cylinder 12 so as to seep out from the oil supply opening 30 and directly lubricates the sliding surface between the piston 13 and the cylinder 12. ing.

An oil sump groove 32 is formed below the piston 13 and below the piston ring 19 so as to be connected to the lower part of the piston ring groove 18. The oil sump groove 32 is formed on the side of the cylinder block 10 facing the exhaust passage 17, and extends from one pin hole 23 in which the piston pin 22 is fitted to a position above the other pin hole 23 by 180 degrees. The length of each pin hole 23
An oil passage 33 is formed which communicates with the pin hole 23 from the oil reservoir groove 32 at a position above the oil reservoir 32 and guides lubricating oil. Therefore, when the piston 13 reciprocates in the cylinder 12, the lubricating oil adhered to the cylinder 12 is efficiently collected in the oil sump groove 32 provided below the piston ring 19, and the lubricating oil is accumulated in the oil sump. The oil passage 33 guides the piston pin 22 from the groove 32 to the pin hole 23 into which the piston pin 22 fits. As a result, the area around the piston pin is lubricated directly with the lubricating oil, so that the area around the piston pin can be lubricated directly and reliably without affecting the engine performance, preventing wear and seizure around the piston pin. it can.

The small end 25 of the connecting rod 24 has
Oil supply holes 34 are formed in communication with the bearing 26,
The atomized lubricating oil is made into a liquid state and supplied to the bearing 26 from the oil supply hole 34. A needle bearing is used as the bearing 26 as shown in FIG.
The bearing cage 260 has holding holes 261 formed at predetermined intervals. The needle 26 is inserted into the holding hole 261.
2 is inserted from the inside, and a caulking portion 263 is provided inside the holding hole 261 to prevent the needle 262 from falling out inside. On the other hand, a flat portion 264 is formed on one side outside the holding hole 261, and an inclined portion 265 is provided on the other side,
Both are formed asymmetrically. Thereby, the flat portion 26
The 4 and the inclined portion 265 prevent the needle 262 from falling out. Further, the connecting rod 24 swings due to the reciprocating motion of the piston 13, and the bearing 26 also rotates with the swinging movement. ,
When viewed at the same crank angle, the bearing 26 rotates in one direction. Therefore, the load from the piston pin 22 is always
6, the bearing 26 is less likely to wear unevenly.

Further, one arm 35 of the crankshaft 4
A circular oil groove 36 is formed on the side of the oil groove 36. An oil passage 37 extends from the oil groove 36 through the crank pin 28 to the other arm 38. further,
An oil passage 39 for guiding oil from the oil passage 37 to the bearing 29 is formed. A plug 100 is provided in the oil passage 37 from the arm 38 side to the vicinity of the oil passage 39, and the plug 100 is prevented from falling off. Therefore, the plug 100
Thus, the oil passages 37 and 39 from the oil groove 36 to the bearing 29 are more directly connected, and the lubricating oil flows from the oil groove 36 through the oil passages 37 and 39 by the rotation of the crankshaft 4 when the engine is started. The bearing 29 is supplied directly to the bearing 29 and can quickly lubricate the bearing 29 even when the engine is started. The oil passage 39 is connected to the connecting rod 2.
4 is formed at a position shifted forward from the position of the top dead center in the rotation direction, thereby preventing a large explosion pressure from being directly applied to the portion where the oil passage 39 is formed.

FIG. 6 is a sectional view showing another embodiment of the crankshaft. In the crankshaft 4, the bottom 40 a of the oil groove 40 formed on the side of the arm 35 is formed eccentric to the crankpin 28 side with respect to the crank rotation center. By eccentrically positioning the bottom 40a of the oil groove 40 toward the crankpin 28, the rotation of the crankshaft 4 collects the lubricating oil along the bottom 40a of the oil groove 40 toward the oil passage 37, and the oil passage 37. , 39
The bearing is directly supplied to the bearing via the shaft, so that the bearing can be quickly lubricated even when the engine is started.

FIG. 7 is a sectional view showing still another embodiment of the crankshaft. In the crankshaft 4, an oil passage 51 is formed so as to extend from the bottom 50 a of the oil groove 50 formed on the side of the arm 35 to the center of the crankpin 28. As described above, by forming the oil passage 51 from the bottom 50a of the oil groove 50 directly through the center of the crankpin 28, the oil passage 51 from the oil groove 50 to the bearing is shortened. In such a case, the bearing can be quickly lubricated.

8 to 10 show another embodiment of the piston. FIG. 8 is a plan view of the piston, and FIG.
FIG. 10 is a cross-sectional view taken along the line IX of FIG. 9. In this embodiment, an oil sump groove 60 is formed below the piston 13 and below the piston ring 19 so as to be connected to the lower part of the piston ring groove 18. The oil sump groove 60 is formed on the side of the cylinder block facing the exhaust passage, and extends from one pin hole 23 in which the piston pin is fitted to a position above the other pin hole 23 by 180.
Oil passages 61 are formed in the oil reservoir grooves 60 at positions above the respective pin holes 23 and open to the tip of the boss portion 21 to guide lubricating oil to the small ends 25 of the connecting rods 24. Have been. Therefore, the lubricating oil attached to the cylinder is efficiently collected by the oil sump groove 60, and the lubricating oil is guided from the oil sump groove 60 to the small end 25 of the connecting rod 24 by the oil passage 61. As a result, the area around the piston pin is lubricated directly with the lubricating oil, so that the area around the piston pin can be lubricated directly and reliably without affecting the engine performance, preventing wear and seizure around the piston pin. it can.

11 to 13 show another embodiment of the piston. FIG. 11 is a plan view of the piston, FIG. 12 is a sectional view taken along line XII--XII of FIG. 11, and FIG. 13 is XIII of FIG.ー
It is sectional drawing which follows the XIII line. In this embodiment, an oil sump groove 70 is formed below the piston ring groove 19 at a predetermined interval below the piston ring 19 at a position below the piston 13. The oil sump groove 70 is formed on the side of the cylinder block opposite to the exhaust passage, and extends from one pin hole 23 into which the piston pin fits to the other pin hole 2.
The oil passage 71 is provided at a length of 180 degrees over the upper position of the pin hole 3 and communicates with the pin hole 23 from the oil sump groove 70 located above the respective pin hole 23 to guide the lubricating oil.
Are formed. Each of the pin holes 23 has a side relief groove 72 formed therein.
2, the lubricating oil guided from the oil passage 71 is further guided in the axial direction of the piston pin. Therefore, the lubricating oil adhered to the cylinder is efficiently collected in the oil sump groove 70, and the lubricating oil is guided from the oil sump groove 70 to the pin hole 23 in which the piston pin is fitted by the oil passage 71, and further the side relief groove 72 Is guided in the axial direction of the piston pin. This allows
Since the area around the piston pin is directly lubricated with the lubricating oil, the area around the piston pin can be lubricated directly and reliably without affecting the engine performance.

14 to 16 show another embodiment of the piston. FIG. 14 is a plan view of the piston, FIG. 15 is a sectional view taken along the line XV--XV of FIG. 14, and FIG.ー XVI
It is sectional drawing which follows a line. In this embodiment, the piston 13
The oil sump groove 80 is located at a predetermined distance below the piston ring groove 18 at a position below the lower piston ring 19.
Are formed. The oil sump groove 80 is formed on the side of the cylinder block facing the exhaust passage, and has a length of 180 degrees from one pin hole 23 where the piston pin is fitted to a position above the other pin hole 23. Then, an opening is formed at the tip of the boss portion 21 from the oil reservoir groove 80 located above each of the pin holes 23, and the small end 25 of the connecting rod 24 is opened.
An oil passage 81 that guides the lubricating oil toward is formed. Therefore, the lubricating oil adhered to the cylinder is efficiently collected in the oil sump groove 80, and the lubricating oil flows from the oil sump groove 80 to the connecting rod 24 through the oil passage 81.
To the small end 25. As a result, the circumference of the ston pin is directly lubricated with the lubricating oil, so that the circumference of the piston pin can be directly and reliably lubricated without affecting the engine performance, and wear and seizure around the piston pin can be prevented. .

In each of the above-described embodiments, the oil sump grooves 32, 60, 70, and 80 are formed on the side of the cylinder block facing the exhaust passage. It is provided at a length of 180 degrees over the position above the hole 23, thereby preventing the unburned carbon from being deposited in the oil sump grooves 32, 60, 70, 80.

[0022]

As described above, according to the present invention, as the piston reciprocates in the cylinder, the lubricating oil adhering to the cylinder is efficiently collected in the oil reservoir groove provided below the piston ring. The lubricating oil is guided to a pin hole or a small end of the connecting rod in which the piston pin is fitted by the oil passage, and the lubricating oil is collected in an oil reservoir groove provided below the piston ring, and the lubricating oil is supplied directly around the piston pin. Lubricate. By providing an oil sump groove from a pin hole in which one piston pin fits on the side opposite to the exhaust passage of the cylinder at a position below the piston ring of the piston and above the other piston pin hole, It is possible to prevent unburned carbon from being deposited in the oil sump groove. In addition, by forming an oil supply opening for supplying lubricating oil between the cylinder and piston on the side of the cylinder corresponding to the oil sump groove when the piston is near the bottom dead center, lubricating oil directly lubricates around the piston pin. Therefore, the circumference of the piston pin can be directly and reliably lubricated without affecting the engine performance, and wear and seizure around the piston pin can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a two-cycle engine.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a cross-sectional view showing the oil supply port of the cylinder block and the oil sump groove of the piston near the bottom dead center of the piston.

FIG. 4 is an enlarged view of a bearing at a small end of a connecting rod.

FIG. 5 is a longitudinal sectional view showing an oil supply port of a cylinder block and an oil sump groove of a piston.

FIG. 6 is a sectional view showing another embodiment of the crankshaft.

FIG. 7 is a sectional view showing still another embodiment of the crankshaft.

FIG. 8 is a plan view of a piston.

FIG. 9 is a sectional view taken along the line IX-IX of FIG.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

FIG. 11 is a plan view of a piston.

FIG. 12 is a sectional view taken along the line XII-XII in FIG. 11;

FIG. 13 is a sectional view taken along the line XIII-XIII in FIG.

FIG. 14 is a plan view of a piston.

FIG. 15 is a sectional view taken along the line XV-XV in FIG. 14;

FIG. 16 is a sectional view taken along the line XVI-XVI in FIG. 15;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankcase 4 Crankshaft 7 Crankcase 12 Cylinder 13 Piston 19 Piston ring 22 Piston pin 23 Pin hole 24 Connecting rod 25 Small end 32 Oil sump groove 33 Oil passage

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01M 1/06 F02F 3/00 F16J 1/08 F16J 1/16

Claims (1)

(57) [Claims] A piston pin for supporting a reciprocally movable piston in a cylinder is connected to a crankshaft pivotally supported by a crankcase by a connecting rod, and a crank chamber connected to the cylinder is used as a primary compression chamber of intake air. In a two-stroke engine, the oil extends from a pin hole in which one piston pin is fitted to a position below the piston ring of the piston and facing the exhaust passage of the cylinder from an upper position of the other piston pin hole. Providing a sump groove, forming an oil supply opening for supplying lubricating oil between the cylinder and the piston on the side of the cylinder corresponding to the oil sump groove when the piston is near the bottom dead center, and the oil sump groove; An oil passage communicating with a pin hole in which the piston pin fits or a small end of the connecting rod and guiding lubricating oil is formed. Two-cycle engine according to claim.