JPH08296420A - Reciprocating internal combustion engine - Google Patents

Abstract

PURPOSE: To splash oil from the large end of a con'rod so as to lubricate the con'rod and a piston by arranging the surface opening of the con'rod in this side, where the con'rod displaces from the cylinder center while the piston is raised from the bottom dead point to the top dead point, of a line connecting respective centers of the small end and the large end of the con'rod each other. CONSTITUTION: An oil path 34 to the large end 6b of a con'rod 6 connected to a piston 5 is formed in the inside of a crankshaft 7. An oil hole 6e extending from the large end 6b of the con'rod 6 to the surface opening 6d of the con'rod 6 is formed. The surface opening 6d is arranged in this side, where the con'rod 6 displaces from the cylinder center L2 while the piston 5 is raised from the bottom dead point to the top dead point, of L1 connecting respective centers of the small end 6a and the large end 6b of the con'rod 6 each other. The small end 6a of the con'rod 6 and the top rear side of the piston 5 are thus effectively lubricated by oil splashed from the large end 6b of the con'rod 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating internal combustion engine which lubricates an engine with oil.

[0002]

2. Description of the Related Art In a reciprocating internal combustion engine, a combustion chamber is formed by a cylinder head, a cylinder body and a piston, and the piston receives the combustion pressure generated in the combustion chamber.
This combustion pressure is transmitted as a rotational force from the pin boss portions provided on both sides in the middle of the longitudinal direction of the piston to the piston pin, and further through the small end and the large end of the connecting rod to the crank shaft arranged in the crank chamber. is there. The air sucked into the crank chamber by the rise of the piston is primarily compressed as the piston descends, and the combustion gas in the combustion chamber is discharged as the piston descends, and the primary compressed air is introduced into the combustion chamber. In such a reciprocating internal combustion engine, oil is sucked up from an oil tank by an oil pump to supply the oil to a cylinder supporting the journal part of the crankshaft arranged in the crank chamber or to the bearing part on the crankcase side, and Some journals have an oil passage that penetrates diagonally, and there is a branch passage that connects this oil passage to the large end of the connecting rod connected to the piston to lubricate the large end. Was properly scattered in the crank chamber.

[0003]

As described above, the large end of the connecting rod is lubricated, and the oil accumulated at the bottom of the crank chamber is returned to the intake pipe upstream of the reed valve through the check valve, and the piston of the connecting rod is returned. Lubrication of the small end connected to the pin or the piston pin side is not sufficient.

The present invention has been made in view of the above point, and a crankcase compression type two-cycle engine capable of effectively lubricating the small end of the connecting rod and the back side of the top of the piston by the oil scattered from the large end of the connecting rod. It is intended to be provided.

[0005]

In order to solve the above-mentioned problems and to achieve the object, the invention according to claim 1 forms a combustion chamber by a cylinder head, a cylinder body and a piston, and generates in this combustion chamber. The combustion pressure is generated by the piston, and this combustion pressure is applied to the crankshaft located in the crank chamber from the pin bosses provided on both sides in the middle of the longitudinal direction of the piston to the piston pin, and further through the small end and the large end of the connecting rod. In the reciprocating internal combustion engine, the oil passage is formed in the crankshaft to the large end of the connecting rod connected to the piston, and the oil hole from the large end of the connecting rod to the surface opening of the connecting rod is formed. The surface opening is a line connecting the centers of the small end and the large end of the connecting rod, and the piston is in the ascending stroke from the bottom dead center to the top dead center. Rod is characterized in that arranged on the side displaced from the cylinder center.

In the reciprocating internal combustion engine according to the second aspect of the present invention, the intake passage is communicated with the crank chamber via the check valve, and the piston rises on the connecting rod side with the communicating position as the boundary of the cylinder. The feature is that it is aimed at the big end when it is in the process of travel.

In the reciprocating internal combustion engine according to the third aspect of the present invention, the intake passage is communicated with the crank chamber via the check valve, and the communicating position is on the side of the connecting rod opposite to the cylinder center. Is characterized by.

In the reciprocating internal combustion engine according to the fourth aspect of the present invention, the combustion chamber is formed by the cylinder head, the cylinder body and the piston, the combustion pressure generated in the combustion chamber is received by the piston, and the combustion pressure of the piston is received. In a reciprocating internal combustion engine, which is configured to transmit a rotational force from a pin boss portion provided on both sides in the middle of the longitudinal direction to a piston pin, and further through a small end and a large end of a connecting rod to a crankshaft arranged in a crank chamber, The piston slidably supports spherical bearings each having a spherical outer surface and a pin hole into which a piston pin into which the connecting rod is rotatably connected is provided in a substantially central portion inside a pin boss portion. The feature is that it is made to.

In a reciprocating internal combustion engine according to a fifth aspect of the present invention, a combustion chamber is formed by a cylinder head, a cylinder body and a piston, the combustion pressure generated in the combustion chamber is received by the piston, and the combustion pressure of the piston is received. In a reciprocating internal combustion engine in which a rotational force is transmitted from a pin boss portion provided on both sides in the middle of the longitudinal direction to a piston pin, and further through a small end and a large end of a connecting rod to a crankshaft, the piston has pin bosses on both sides. A straight pin hole is provided in the portion, while the piston pin has a tapered outer shape at both ends, and a second taper having a larger inclination angle at the end of the first tapered portion. It is characterized by forming a part.

[0010]

According to the first aspect of the invention, the crankshaft rotates to scatter from the large end, and scatter to the small end of the connecting rod and the backside of the top of the piston for lubrication.

According to the second aspect of the present invention, the intake passage is communicated with the crank chamber through the check valve, and the communication position is small on the connecting rod side with the cylinder center as a boundary and when the piston is in the upward stroke. The flow of air from the intake passage stochastically increases the amount of oil scattered from the large end by the rotation of the crankshaft to the small end of the connecting rod and the back side of the top of the piston for lubrication.

According to the third aspect of the present invention, the intake passage is communicated with the crank chamber via the check valve, and the communication position is on the side of the connecting rod opposite to the center of the cylinder. Since the air flow is along the direction of rotation of the crankshaft, a larger amount of oil is stochastically scattered from the large end to the small end of the connecting rod and the backside of the top of the piston for lubrication.

According to the fourth aspect of the present invention, the piston slidably supports spherical bearings each having a pin hole into which a piston pin is inserted in the pin boss portion, and the spherical bearings are used to influence thermal deformation. Correct and make it function normally, and prevent wear inside the pin boss.

According to the fifth aspect of the present invention, the piston has straight pin holes in the pin boss portions on both sides, while the piston pin has tapered outer shapes at both ends, and the end portion of the first tapered portion is formed. A second taper portion having a larger inclination angle is formed on the inner surface of the pin boss to prevent abrasion inside the pin boss portion.

[0015]

Embodiments of the reciprocating internal combustion engine of the present invention will be described below with reference to the drawings. 1 is a cross-sectional view of a reciprocating internal combustion engine, FIG. 2 is a view showing a connecting rod connecting a piston and a crankshaft, FIG. 3 is a view showing a lubricating system, FIG. 4 is a view showing lubrication on a piston pin side, and FIG. 5 is a diagram showing the timing of oil scattering.

The reciprocating internal combustion engine 1 is a crank chamber compression type two-cycle three-cylinder diesel engine. In the reciprocating internal combustion engine 1, a cylinder body 3 and a cylinder head 4 are fastened together on a crankcase 2. ing. The piston 5 slidably inserted into the cylinder bore 3a of the cylinder body 3 is connected to the crankshaft 7 in the crankcase 2 via the connecting rod 6.

The cylinder head 4 has a two-part structure of a lower head 8 and an upper head 9. A sub-combustion chamber 10a is formed at a boundary portion between the two, and the sub-combustion chamber 10a is formed by a passage 8a having a small diameter so that the combustion chamber 10b of the cylinder bore 3a is formed.
Is in communication with. The tip ends of the glow plug 11 for starting ignition and the fuel injection valve 12 face the auxiliary combustion chamber 10a.

A crank chamber 2a is formed by the crankcase 2 and the cylinder body 3, and an intake opening 3b communicating with the crank chamber 2a is formed in the cylinder body 3. An intake pipe 13 is connected to the intake opening 3b. A reed valve 14 is arranged in the intake opening 3b to allow intake of the crank chamber 2a, prevent backflow, and perform primary compression of fresh air in the crank chamber 2a.

At the approximate center of the cylinder body 3 in the height direction,
Two first scavenging ports 15a, 15a and one second scavenging port (not shown) are formed in the front-rear direction, and each communicates with the crank chamber 2a via a scavenging passage (not shown). A main exhaust port 16a is formed in the upper part of the cylinder body 3 so as to face the second scavenging port, and the main exhaust port 16a is led out to the outer wall of the cylinder by a main exhaust passage 16b continuous with the main exhaust port 16a. A pair of auxiliary exhaust ports 17a, 17a are formed slightly above the main exhaust port 16a in the axial direction of the cylinder bore with a space provided in the circumferential direction of the cylinder bore 3a. Sub exhaust port 17a
Each of the auxiliary exhaust passages 17b connected to the main exhaust passage 16b merges with the main exhaust passage 16b on the downstream side and is exhausted through the exhaust pipe 18.

The auxiliary exhaust passage 17b, which is in the middle of the exhaust passage for guiding the exhaust gas from the combustion chamber 10b, intersects with the auxiliary exhaust passage 17b and penetrates at least a part of the auxiliary exhaust passage 17b, so that the exhaust passage cross-sectional area is variable. Exhaust valve 1 that can be fully closed
9 is arranged, and the exhaust valve 19 is driven by the drive device 21.

Next, the lubrication of the bearing portion of the connecting rod 6 will be described with reference to FIGS. 2 to 5. The small end 6a of the connecting rod 6 is provided on a piston pin 31 via a bearing 30 as shown in FIG.
Are inserted into the pair of pin boss portions 5a. The large end 6b of the connecting rod 6 is provided on the crank pin 33 via the bearing 32, and the crank pin 33 is provided on the crank shaft 7. In the crankshaft 7, oil passages 34 and 35 are formed which communicate with the bearing 32 from the crank web end surface 7a which communicates with the oil reservoir space in the journal bearing portion 39,
Oil is introduced into the large end 6b of the connecting rod 6 and the bearing 32 for lubrication.

The reciprocating internal combustion engine 1 is provided with an ECU 200, and the ECU 200 controls the drive of the oil pump 201 based on the engine speed and load information. By driving the oil pump 201, oil is guided from the oil tank 202 to the oil pump 201 via the oil filter 203. When the oil pump 201 is driven, the oil is supplied to the first cylinder crank journal portion 501 via the oil distribution pipe 204.
a, a first cylinder cylinder inner wall discharge port 501b, a second cylinder crank journal part 502a, a second cylinder cylinder inner wall discharge port 502b, a third cylinder crank journal part 503a, and a third cylinder cylinder inner wall discharge port 503b. Supply to.

The oil guided to the first cylinder crank journal portion 501a is introduced into the journal bearing portion 39 from the oil passage 300. The journal bearing portion 39 is composed of an outer cage 39 a and a needle 39 b, and the journal bearing portion 39 is sealed by a seal body 301. The oil introduced from the oil passage 300 to the journal bearing portion 39 is the oil hole 39c of the outer cage 39a.
Is guided to the needle 39b for lubrication, and is guided to the ring-shaped oil groove 7b formed on the crank web end surface 7a. Further, the oil is guided from the ring-shaped oil groove 7b to the oil passages 34 and 35 formed in the crank pin 33. That is, the end portion of the outer cage 39a of the journal bearing portion 39 slightly projects into the oil groove 7b,
Since the gap between the outer periphery of the outer cage 39a and the inner periphery of the oil groove 7b on the large diameter side is small, almost no oil passes through this gap and is directly ejected into the crank chamber 2a. Almost all of the oil supplied to the journal bearing portion 39 is sent from the oil passages 34, 35 in the crankshaft 7 to the outer peripheral portion of the crankpin 33.

The oil supplied to the discharge port portion 501b of the inner wall of the first cylinder cylinder is in the vicinity of the second piston ring 311 located below the first piston ring 310 when the piston 5 is at the bottom dead center in FIG. It is discharged from the discharge port to the inner wall of the cylinder at the portion.

The supply of oil to the second cylinder crank journal portion 502a and the second cylinder cylinder inner wall discharge port portion 502b is similarly configured, and the third cylinder crank journal portion 503a and the third cylinder cylinder inner wall discharge port portion 503b are also configured.
The oil supply to the oil is similarly configured.

A bearing 32 is arranged between the outer peripheral portion of the crank pin 33 and the inner periphery of the connecting rod large end 6b, and the bearing 32 comprises a needle 32a and a retainer 32b. In particular,
Oil is guided to the space 32c between the needle 32a and the needle 32a separated by the retainer 32b, and is further guided to the surface opening 6d from the oil reservoir groove 6c and the oil hole inlet 6f through one oil hole 6e. .

An oil pool groove 6c is formed on the large end 6b of the connecting rod 6 on the small end side of the inner peripheral surface.
An oil hole 6e is formed from the oil sump groove 6c at the large end 6b of the connecting rod 6 to the surface opening 6d of the connecting rod 6, and the surface opening 6d is formed on the piston 5 of the line L1 connecting the centers of the small end 6a and the large end 6b of the connecting rod 6. Is arranged on the side where the connecting rod 6 is displaced from the cylinder center L2 during the ascending stroke from the bottom dead center to the top dead center.

Oil is jetted into the crank chamber 2a through the minimum clearance (both sides) between the side wall 33a of the crank pin 33 on the bearing side and the bearing hole end 6g of the connecting rod large end 6b. Because it is difficult to pass through a narrow gap,
Eruption is small. Further, since the total area of the minimum clearance is substantially equal to or larger than the area of the oil hole inlet 6f due to the length of the narrow clearance portion being increased, the oil hole inlet 6 is
If the total area of the minimum clearance is made smaller than the area of f, the amount of oil that passes through the minimum clearance and is ejected into the crank chamber 2a becomes almost zero.

The oil pool groove 6 at the large end 6b of the connecting rod 6
As shown in FIG. 5, when the rotation of the crankshaft 7 is clockwise, the piston 7 moves to the bottom dead center B.c. D. Top dead center T.C. D. From the midpoint a during the ascending stroke to C to the top dead center T.I.
D. Oil accumulates in the oil sump groove 6c in a period until slightly passing C. The oil accumulated in the oil sump groove 6c at the large end 6b of the connecting rod 6 is guided by the centrifugal force generated by the rotation of the crankshaft 7 to the surface opening 6d at the center of the side surface of the connecting rod 6 and the small end of the connecting rod 6 from the surface opening 6d. 6
Lubricate by scattering to a and the back side of the piston top. The oil scattering and discharge 101 also splashes on the gaps 100 on both sides between the small end 6a of the connecting rod 6 and the piston boss 5a (FIG. 4).

The timing b at which the oil is scattered is determined by the position of the surface opening 6d, the size of the surface opening 6d, the crankshaft rotation speed, and the like. In this embodiment, the size of the surface opening 6d is set to 1/40 to 1/1 / the cylinder bore diameter.
50, and the oil hole 6e is at the angle of alpha = 15 ° to 45 ° from the center of the connecting rod 6, and the connecting rod large end 6b is formed.
It is formed toward the center of the crank pin hole (Fig. 2). As a result, the oil scattered from the large end 6b due to the rotation of the crankshaft 7 can be stochastically increased in quantity.

Next, the arrangement position of the intake opening 3b will be described. In the embodiment of FIG. 6, the intake opening 3b communicates with the crank chamber 2a via the reed valve 14 which is a check valve, and the communicating position is on the connecting rod 6 side and the piston 5 with the cylinder center L2 as a boundary. The intake opening 3b is formed so as to face the large end 6b of the connecting rod 6 during the ascending stroke. In this way, since the communication position of the intake opening 3b is directed to the connecting rod 6 side and the large end 6b when the piston 5 is in the ascending stroke with the cylinder center L2 as a boundary, the air from the intake opening 3b is The oil that flows from the large end 6b due to the flow and the rotation of the crankshaft 7 more accurately and effectively scatters and lubricates the small end 6a of the connecting rod 6 and the back side of the piston top.

In the embodiment of FIG. 7, the intake opening 3b is communicated with the crank chamber 2a via the reed valve 14 which is a check valve.
This communication position is on the opposite connecting rod side with the cylinder center L2 as a boundary, and the top dead center T.I. D. Although it is provided at a position X close to C, the bottom dead center B.I. D. It can be provided at a position Y close to C, or an intermediate position Z between them.

In this way, the reed valve 1 is connected to the crank chamber 2a.
4 communicates with the intake opening 3b, and this communication position is on the opposite connecting rod side with the cylinder center L2 as a boundary, and the air flow from this intake opening 3b is the crankshaft 7
Since the oil is scattered along the rotation direction of, the oil scattered from the large end 6b is stochastically scattered to the small end 6a of the connecting rod 6 and the back side of the top of the piston for lubrication.

Another embodiment of the oil hole 6e provided in the connecting rod 6 will be described with reference to FIGS. 2, 8 and 9. Two oil holes 6e are formed in the connecting rod 6, similarly to the oil hole 6e in FIG.
It is formed toward the center of the crank pin hole of the large end 6b of the connecting rod 6 at an angle of α15 ° to 45 ° from the center of the connecting rod 6. The surface opening 6d of the oil hole 6e is shown in FIG.
Further, as shown in FIGS. 9A and 9B, they are located on both sides of the connecting rod 6 while being separated in the crankshaft direction. Then, at least a part of the surface opening 6d is a rib 6g of the connecting rod 6.
Located outside. As a result, the oil scattering flow 101
Means that the small end 6a of the connecting rod 6 will surely land due to the gaps 100 on both sides between the piston bosses 5a.
The lubrication around the piston pin 31 will be carried out more reliably. The oil hole 6e and the surface opening 6d are
As shown in FIGS. 9 (a) and 9 (b), the positions are matched on the front side and the back side, but as shown in FIG. 9 (c), the positions may be shifted on the front side and the back side.

Next, regarding lubrication of the piston 5, FIG.
This will be described with reference to FIGS. 10 is a side view of the piston, FIG. 11 is a sectional view taken along line XI-XI of FIG. 10, and FIG.
11 is a sectional view taken along line XII-XII in FIG. 11, and FIG. 13 is X in FIG.
It is a sectional view taken along the line III-XIII.

In this embodiment, a pin insertion hole 5b is formed in the pin boss portion 5a of the piston 5, and this pin insertion hole 5b is formed.
Piston pin 31 is inserted through spherical bearing 40 into
It is prevented from coming off by a circlip 41. An escape portion 5c is formed in the pin insertion hole 5b, and the spherical bearing 40 is inserted from this escape portion 5c for assembly.

The pin boss portion 5a may be deformed due to thermal expansion during operation, and the inner diameter of the pin boss portion 5a may be worn due to high surface pressure of the pole portion. As a countermeasure for some pistons, the inner diameter of the pin boss portion 5a is treated with alumite or the like. However, when the heat load is severe, it is insufficient as a measure against wear.

In this embodiment, since the piston pin 31 is rotatably supported by the spherical bearing 40, the spherical bearing 40 corrects the effect of thermal deformation in the piston 5 having a large heat load such as a two-cycle diesel engine, and the pin boss is used. It is possible to keep the function of the bearing normal and prevent damage such as abrasion of the inner diameter of the pin boss portion 5a. Further, since the deformation of the piston pin 31 is reduced, the life of the bearing of the small end 6a of the connecting rod 6 is improved. Furthermore, since the piston 5 is free in the spherical bearing 40, the sliding loss between the piston 5 and the cylinder wall surface is reduced.

Note that, in FIG. 11, between the inner diameter A of the pin insertion hole 5b and the inner diameter B of the spherical bearing 40, A> B is set. Accordingly, even if the connecting rod 6 and the piston 5 are relatively displaced, the problem that the piston pin 31 interferes with the pin hole 5b and sticks to each other does not occur. As a result, the spherical bearing 40 can normally maintain the function as a pin boss bearing forever.

FIG. 14 is a side view of the piston. In this embodiment, as in the previous embodiment, the escape portion 5 is provided in the pin hole 5b.
c is formed, the relief portion 5c is formed to be inclined with respect to the piston axial direction, and the spherical bearing 40 is inserted from the relief recess portion 5c for assembly. In this example,
Oil can be guided from the cylinder wall surface to the piston pin 31 side.

FIG. 15 shows an example in which the piston pin 31 is directly supported by the pin boss portion 5a in a two-cycle crankcase compression type, swirl chamber fuel injection type diesel engine to which the present invention is applied.

In the conventional two-cycle gasoline engine in which fuel is supplied to the intake passage, the fuel is vaporized in the crank chamber and the piston 5 is cooled from the crank chamber side. Does not cool the piston 5 from the crank chamber side. Therefore, the temperature of the piston 5 easily rises and thermal deformation is large. Further, the diesel engine has a higher combustion pressure than the gasoline engine, and the combustion pressure acting on the top of the piston is large. Therefore, when the engine is stopped and the engine is cold, the straight pin hole 5b is thermally deformed during operation, and the combustion pressure acts on the top of the piston 5, while the reaction force from the connecting rod 6 side causes the pin boss portion via the piston pin 31. Since it acts on 5a, the pin hole 5b is also deformed during operation. Therefore, in the present swirl chamber fuel injection type diesel engine, the contact surface pressure between the piston pin 31 and the pin hole 5b of the pin boss 5a at the end of the piston pin 31 becomes large, and the pin hole 5b is worn and deformed for a long period of time. There was a problem that it became difficult to drive.

As a solution to this problem, the first taper portion 3 in which the outer dimension of the end portion of the piston pin 31 is tapered to reduce the outer dimension thereof
It is conceivable to reduce the contact surface pressure at the end of the piston pin 31 even if the pin hole 5b is deformed relative to the piston pin 31 by forming 1b.

As a result, the contact surface pressure at the end of the piston pin 31 can be reduced, and wear deformation of the pin hole 5b can be prevented.

However, at the portion where the corner between the end surface 31a of the piston pin 31 and the first tapered portion 31b contacts the pin hole 5b, the contact surface pressure should change rapidly from 0 at this corner. become. Even if the contact surface pressure of the first taper portion 31b is equal to or less than the allowable value, stress concentration occurs at a portion where the contact surface pressure changes rapidly from 0, and the contact surface pressure is very partially within the allowable value. Will be exceeded. For this reason,
Wear deformation of the pin hole 5b still occurs at the end of the first tapered portion 31b, and this small wear deformation serves as a starting point.
It is conceivable that piston damage may occur, which causes operation failure during long-term operation.

The piston pin 31 in FIG. 15 has an outer diameter of 23 mm and a total length of 65.5 mm, and has end faces 31 at both ends.
Outer taper (one side inclination 1/10)
It is processed into a (00) shape. Furthermore, from the end face 31a to 5
The range of mm is processed into an outer taper (inclination on one side is 1/3000). That is, it is formed in a two-step tapered shape. On the other hand, the upper side of the pin hole 5b is 22 mm from the circlip 150 for preventing the piston pin 31 from coming off. Therefore, when the engine is not operating, the piston pin 31 is in contact with the pin hole 5b only 2 mm closer to the center of the pin hole 5b. When the explosion pressure is applied during operation, the piston pin 31 is elastically deformed by receiving a downward load from the pin hole 5b at the central portion of the piston pin 31 by the connecting rod 6 and elastically deforming at the inner first tapered portion 31b. Pin hole 5b
The contact surface pressure can be reduced. Moreover, since the end portion of the first tapered portion 31b is formed in a tapered shape with a larger inclination, stress concentration is relieved. The second taper portion 31d of the second stage has a radius of 8
You may form in the spherical shape of 00-900. Further, it is more preferable to chamfer the yarn at the corners between the second taper portion 31d and the end surface 31a of the second stage, that is, chamfering at 45 ° of 0.5 to 1 mm.

The present invention can be applied not only to diesel engines but also to gasoline engines.

[0048]

As described above, according to the first aspect of the invention, the crankshaft is rotated to scatter from the large end, to the small end of the connecting rod and to the back side of the top of the piston, and special processing or structure is made on the piston side. Can be effectively lubricated by oil.

According to the second aspect of the present invention, the intake passage is communicated with the crank chamber via the check valve, and the communication position is small on the connecting rod side with the cylinder center as the boundary and when the piston is in the upward stroke. Since the oil is directed toward the end, the amount of oil scattered from the large end by the rotation of the crankshaft due to the flow of air from the intake passage is stochastically increased to the small end of the connecting rod and the back side of the top of the piston for lubrication.

According to the third aspect of the present invention, the intake passage is communicated with the crank chamber via the check valve, and the communication position is on the side of the connecting rod opposite to the cylinder center. Since the air flow is along the rotation direction of the crankshaft, more oil is scattered from the large end stochastically and can be scattered to the small end of the connecting rod and the back side of the top of the piston for lubrication.

According to the fourth aspect of the invention, since the pistons slidably support the spherical bearings having the pin holes into which the piston pins are inserted, the spherical bearings are affected by thermal deformation. To correct it and make it function normally.
Moreover, it is possible to prevent wear inside the pin boss portion.

According to a fifth aspect of the present invention, the piston is provided with straight pin holes in the pin boss portions on both sides, while the piston pin has a tapered outer shape at both ends.
Since the second taper portion having a larger inclination angle is formed at the end of the taper portion, it is possible to prevent it from becoming the starting point of wear deformation and suppress the occurrence of piston damage that causes inoperability during long-term operation. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a crankcase compression type two-cycle engine.

FIG. 2 is a diagram showing a connecting rod that connects a piston and a crankshaft.

FIG. 3 is a diagram showing a lubrication system.

FIG. 4 is a diagram showing lubrication on the piston pin side.

FIG. 5 is a diagram showing an oil scattering timing.

FIG. 6 is a diagram showing an arrangement position of an intake passage.

FIG. 7 is a view showing another embodiment of the arrangement position of the intake passage.

FIG. 8 is a diagram showing lubrication on the piston pin side.

FIG. 9 is a diagram showing positions of oil holes and surface openings.

FIG. 10 is a side view of the piston.

11 is a sectional view taken along line XI-XI of FIG.

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

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

FIG. 14 is a side view of a piston according to another embodiment.

FIG. 15 is a side view of a piston according to still another embodiment.

[Explanation of symbols]

 3 Cylinder body 4 Cylinder head 5a Pin boss 5 Piston 6 Connecting rod 6a Small end 6b Large end 6d Surface opening 6e Oil hole 7 Crankshaft 10b Combustion chamber 34 Oil passage

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area F16J 1/16 F16J 1/16

Claims (5)

[Claims] 1. A combustion chamber is formed by a cylinder head, a cylinder body, and a piston, and a combustion pressure generated in the combustion chamber is received by the piston, and the combustion pressure is provided on both sides in the middle of the longitudinal direction of the piston. From the piston pin to the piston pin, and further through the small end and the large end of the connecting rod to transmit as a rotational force to the crankshaft arranged in the crank chamber, in the reciprocating internal combustion engine, the connecting rod connected to the piston in the crankshaft is An oil passage is formed to the large end, and an oil hole is formed from the large end of the connecting rod to the surface opening of the connecting rod.The surface opening is a line connecting the centers of the small end and the large end of the connecting rod, and the piston is A reciprocating internal combustion engine, wherein the connecting rod is arranged on the side displaced from the cylinder center during the ascending stroke from bottom dead center to top dead center. 2. An intake passage is communicated with the crank chamber via a check valve, and the communicating position is directed to the connecting rod side with the cylinder center as a boundary and toward the large end when the piston is in the upward stroke. The reciprocating internal combustion engine according to claim 1, wherein 3. The reciprocating type according to claim 1, wherein an intake passage is communicated with the crank chamber via a check valve, and the communicating position is on the side of the connecting rod opposite to the cylinder center. Internal combustion engine. 4. A combustion chamber is formed by a cylinder head, a cylinder body and a piston, and a combustion pressure generated in the combustion chamber is received by the piston, and the combustion pressure is provided on both sides in the middle of the longitudinal direction of the piston. In the reciprocating internal combustion engine, in which the rotational force is transmitted to the crankshaft disposed in the crank chamber through the small pin and the large end of the connecting rod, and to the crankshaft disposed in the crank chamber, the piston has a spherical outer surface inside the pin boss portion. The spherical bearings each having a pin hole into which the piston pin into which the connecting rod is rotatably connected are provided in a substantially central portion are slidably supported. Reciprocating internal combustion engine. 5. A combustion chamber is formed by a cylinder head, a cylinder body and a piston, the combustion pressure generated in the combustion chamber is received by the piston, and the combustion pressure is provided on both sides in the middle of the longitudinal direction of the piston. In the reciprocating internal combustion engine, in which the rotational force is transmitted to the crankshaft via the small end and the large end of the connecting rod, the piston has straight pin holes in the pin boss portions on both sides. On the other hand, the piston pin is characterized in that both ends thereof are formed in a tapered outer shape, and a second taper portion having a larger inclination angle is formed at an end portion of the first taper portion. Reciprocating internal combustion engine.