JP2011117459A - Piston - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston of an internal combustion engine, which prevents the oil flowing reversely in a cooling cavity and the oil supplied newly into the cooling cavity from interfering with each other. <P>SOLUTION: The piston 7 is formed with the cooling cavity 10 therein in which the oil circulates for cooling the piston 7. Two curved guides 21, 21 of a plate shape are provided in a supply part 12 of the cooling cavity 10, extending from an opening 12a to the inside of a circulation part 11 through the supply part 12. An introduction path 22 is composed between the two guides 21, 21. Discharge paths 23, 23 are composed outside the guides 21, 21, respectively. The inlet 22a of the introduction path 22 and the outlets 23b of the discharge paths 23 are flushed each other and compose the opening 12a of the supply part 12. The outlet 22b of the introduction path 22 is situated inside the circulation part 11 and the inlets 23a of the discharge paths 23 are formed on the bottom 11a of the circulation part 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piston, and more particularly to cooling of a piston of an internal combustion engine.

Since the piston of an internal combustion engine is always exposed to high temperature and high pressure during operation of the internal combustion engine, it is necessary to cool the piston. For example, as described in Patent Document 1, an annular cooling cavity is provided in a piston, and oil is supplied and circulated in the cooling cavity by an oil jet that ejects a part of the oil flowing through the oil gallery. The way is done.
FIG. 9 is a sectional view of a part of the cooling cavity provided in the piston. As shown in FIG. 9, such a cooling cavity 90 includes a supply portion 91 to which oil is supplied and a tubular circulation portion 92 formed over the entire circumference of the piston. The oil supplied from the supply unit 91 circulates in the circulation unit 92 in the circumferential direction of the piston (arrows A and A ′) and is discharged from a discharge unit (not shown). As the oil circulates in the circulation section 92, the oil cools the piston by removing heat from the piston.
Japanese Utility Model Publication No. 61-23635

  However, since the piston always reciprocates in the vertical direction during operation of the internal combustion engine, vertical acceleration is generated in the piston, thereby generating an inertial force in the oil in the circulation portion 92. Then, a part of the oil supplied into the circulation part 92 flows backward toward the supply part 91 (arrows B and B '). This backflowed oil interferes with the oil (arrow C) that is newly supplied to the supply unit 91, thereby hindering the introduction of oil into the circulation unit 92.

  The present invention has been made to solve such a problem, and provides a piston in which oil that flows backward in the cooling cavity and oil supplied to the cooling cavity do not interfere with each other. With the goal.

  A piston according to the present invention is a piston that moves up and down in a cylinder provided inside a cylinder block of an internal combustion engine, and is in communication with an annular cylindrical tube formed in the piston, Supplyed from an oil jet provided in a cylinder block in a piston having a cooling cavity having a supply portion to which oil is supplied and a discharge portion that is in communication with the annular cylindrical tube and discharges oil that has circulated through the annular cylindrical tube When the oil is injected toward the part, the oil is supplied to the supply part, and the supply part is separated by the introduction path through which the oil supplied to the supply part is introduced into the annular cylindrical tube, and the introduction path and the guide. And a discharge path through which oil that flows backward in the annular cylindrical tube toward the supply portion is discharged. Since the introduction path through which the oil supplied to the supply unit is introduced into the annular cylindrical tube is separated from the discharge path through which the oil flows back from the annular cylindrical tube to the supply unit, the respective oils do not interfere with each other.

The guide may be formed in a plate shape and extend to the inside of the annular cylindrical tube.
The length of the guide in the annular cylindrical tube is preferably 1/2 to 2/3 of the inner diameter of the annular cylindrical tube. The oil flowing backward from the annular cylindrical tube to the supply portion and the oil supplied to the supply portion flow through the discharge route and the introduction route reliably, and the oil flowing through the introduction route is easily introduced into the annular cylindrical tube. .
The surface facing the discharge path of the guide may protrude in the opposite direction to the introduction path toward the upper end. The oil that flows back from the annular cylindrical tube to the supply portion flows along the surface facing the discharge path of the guide, so it surely flows into the discharge path.
The inlet of the introduction path may be wider than the outlet of the introduction path. The oil supplied to the supply unit surely flows into the introduction path.
The surface of the guide facing the discharge path protrudes in the opposite direction to the introduction path toward the lower end, and the vicinity of the outlet of the discharge path may be bent in the opposite direction to the introduction path. Since the oil flowing through the discharge path is discharged from the discharge path so as to be away from the oil supplied to the supply unit, the oils are less likely to interfere with each other.

  According to the present invention, in the supply part of the cooling cavity where the oil for cooling the piston circulates, the introduction path through which the oil supplied to the supply part rises, and the discharge path through which the oil flowing back in the circulation part is discharged Therefore, the oils can be prevented from interfering with each other.

1 is a partial cross-sectional view of a diesel engine provided with a piston according to Embodiment 1 of the present invention. 3 is a cross-sectional view of a cooling cavity provided in the piston according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of a modified example of the cooling cavity provided in the piston according to Embodiment 1. 6 is a cross-sectional view of a cooling cavity provided in a piston according to Embodiment 2. FIG. 6 is a cross-sectional view of a cooling cavity provided in a piston according to Embodiment 3. FIG. FIG. 10 is a cross-sectional view of a modified example of a cooling cavity provided in a piston according to Embodiment 3. FIG. 12 is a cross-sectional view of another modification of the cooling cavity provided in the piston according to Embodiment 3. 6 is a cross-sectional view of a cooling cavity provided in a piston according to Embodiment 4. FIG. It is sectional drawing of the conventional cooling cavity part.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
The piston according to the first embodiment will be described by taking as an example a case where it is used in a diesel engine that is an internal combustion engine.
As shown in FIG. 1, the diesel engine 1 includes a cylinder block 2. A cylinder 6 is provided above the cylinder block 2 and a crank chamber 4 is provided below. A crankshaft 5 is rotatably provided in the crank chamber 4. A piston 7 is accommodated in the cylinder 6 so as to reciprocate in the vertical direction. The piston 7 is connected to the crankshaft 5 via a connecting rod 8.
A cooling cavity 10 in which oil for cooling the piston 7 circulates is formed in the piston 7. The cooling cavity portion 10 includes a circulation portion 11 that is an annular cylindrical tube formed in the piston 7 over the entire circumference, and a supply portion 12 and a discharge portion 13 that communicate with the circulation portion 11 and extend vertically downward. The supply unit 12 and the discharge unit 13 are cylindrical tubes, and the lower ends thereof open toward the crank chamber 4.
The cylinder block 2 is provided with a nozzle-like oil jet 15 that communicates with the oil gallery 14 and ejects part of the oil in the oil gallery 14. The tip 15 a of the oil jet 15 faces the opening 12 a of the supply unit 12, and the oil ejected upward from the oil jet 15 is supplied into the supply unit 12.

FIG. 2 is a cross-sectional view of a connection portion between the circulation unit 11 and the supply unit 12 in the cooling cavity 10.
As shown in FIG. 2A, two curved plate-shaped guides 21 and 21 extending from the opening 12 a to the inside of the circulation unit 11 are provided in the supply unit 12. Yes. The length L of the guide 21 in the circulation part 11 is ½ of the opening diameter R of the circulation part 11. If the length L is too small, the effect of separating the backflowing oil from the newly supplied oil is reduced. Conversely, if the length L is too large, the front opening for introducing the oil into the circulation section 11 is narrowed. Oil is difficult to be introduced into the circulation unit 11. Considering these, it is preferable to set the value of L to 1/2 to 2/3 of the opening diameter R.
FIG. 2B is a cross-sectional view taken along the line IIb-IIb in FIG. As shown in FIG. 2B, since the plate-like guide 21 is curved, an introduction path 22 having a substantially circular cross section is formed between the two guides 21 and 21. Discharge paths 23 and 23 having a crescent-shaped cross section are formed outside the guides 21 and 21, respectively.
Further, as shown in FIG. 2A, the inlet 22 a of the introduction path 22 and the outlet 23 b of the discharge path 23 are flush with each other and constitute the opening 12 a of the supply unit 12. The outlet 22 b of the introduction path 22 is located inside the circulation part 11, and the inlet 23 a of the discharge path 23 is formed at the bottom part 11 a of the circulation part 11.
The guides 21 and 21 can be formed by casting or driving, for example.

Next, the operation for cooling the piston according to the first embodiment will be described.
As shown in FIG. 1, when the diesel engine 1 is started, the piston 7 reciprocates in the cylinder 6 by a propulsive force obtained from an explosion in an intake / compression process in a combustion chamber (not shown) in the cylinder 6. The reciprocating motion of the piston 7 is converted into the rotational motion of the crankshaft 5 through the connecting rod 8. The temperature of the piston 7 rises when it is exposed to combustion gas in a combustion chamber (not shown). For this reason, oil is circulated in the cooling cavity 10 to cool the piston 7.

  The oil is supplied to the cooling cavity 10 by ejecting a part of the pressurized oil flowing through the oil gallery 14 from the oil jet 15 to the supply part 12 of the cooling cavity 10. As shown in FIG. 2A, the oil ejected upward from the oil jet 15 mainly flows into the introduction path 22 and rises in the introduction path 22. The oil rising in the introduction path 22 collides with the upper surface 11b of the circulation part 11 and is introduced into the circulation part 11 by changing the direction in the circumferential direction (arrows D and D ') of the piston 7. The oil introduced into the circulation part 11 circulates in the circulation part 11 in the directions of arrows D and D ′, is discharged from the discharge part 13 (see FIG. 1), and is not shown in the figure below the crank chamber 4. Collected in bread. When the oil circulates in the circulation part 11, the oil cools the piston 7 by removing heat from the piston 7.

  Here, as already described, since the piston 7 reciprocates in the vertical direction, the piston 7 generates acceleration in the vertical direction, so that an inertia force in the vertical direction is generated in the oil circulating in the circulation portion 11. Thereby, the oil flows backward toward the supply unit 12 (arrows E and E ′), and the oil may be discharged from the supply unit 12. However, the oil that flows back in the circulation section 11 flows into the discharge path 23 from the inlet 23a of the discharge path 23 by the guide 21 and descends in the discharge path 23 and is discharged from the outlet 23b. The discharged oil is collected in an oil pan below the crank chamber 4. That is, most of each oil circulates through separate paths of the discharge path 23 and the introduction path 22 and therefore does not interfere with each other.

  As described above, the curved guides 21 and 21 are provided in the supply section 12 of the cooling cavity 10 so as to reach the inside of the circulation section 11 from the opening 12a of the supply section 12, and the introduction path 22 is provided in the supply section 12. And the discharge path 23, most of the oil flowing back from the circulation section 11 to the supply section 12 and the oil supplied to the supply section 12 are separated into the discharge path 23 and the introduction path 22 in the supply section 12, respectively. The oil can be prevented from interfering with each other.

As for the length of the supply unit 12, at least when the piston 7 reaches bottom dead center, the tip 15a of the oil jet 15 enters the introduction path 22 as in the cooling cavity 30 shown in FIG. It is preferable to design as follows. By doing in this way, all of the newly supplied oil will rise in the introduction path 22, and it can prevent reliably that each oil interferes with each other.
Further, the length L of the guide 21 in the circulation part 11 is preferably 1/2 to 2/3 of the opening diameter R of the circulation part 11, but is not limited to this range. Even if it is smaller than 1/2 of the opening diameter R, the effect of separating the backflowing oil from the newly supplied oil is reduced, but it is effective as compared with the case where there is no guide. Furthermore, the guide 21 does not need to extend to the inside of the circulation part 11, and the upper end of the guide 21 may be flush with the inlet 23a of the discharge path 23 or lower.

Embodiment 2. FIG.
Next, a piston according to Embodiment 2 of the present invention will be described with reference to FIG. In the following embodiments, the same reference numerals as those in FIGS. 1 and 2 are the same or similar components, and thus detailed description thereof is omitted.
The piston according to the second embodiment is shaped so that the surface facing the discharge path 23 protrudes in the horizontal direction toward the upper end at both end portions of the guide 21 with respect to the first embodiment. is there. Furthermore, the shapes of the introduction path 22 and the discharge path 23 are changed.

  As shown in FIG. 4, in the cooling cavity 40, the lower end 21 b of the guide 21 protrudes below the opening 12 a of the supply unit 12, and the upper end 21 a is positioned inside the circulation unit 11. Yes. The length L of the portion of the guide 21 in the circulation portion 11 is ½ of the opening diameter R of the circulation portion 11. The surface 21c facing the discharge path 23 has a shape that protrudes sharply in the horizontal direction while having concave curved surfaces 21a1 and 21b1 as it goes toward the upper end 21a and the lower end 21b. A surface 21d of the guide 21 facing the introduction path 22 is formed in a chamfered shape at the lower end portion 21b, so that the inlet 22a of the introduction path 22 is wider than the outlet 22b.

  In addition, the inner peripheral surface 12b of the supply unit 12 extends vertically downward from the circulation unit 11, and then extends downward with an inclination so that the inner diameter of the supply unit 12 increases. Thereby, the outlet 23b of the discharge path 23 is wider than the inlet 23a. Further, the lower end portion 21b of the guide 21 protrudes downward from the opening 12a of the supply unit 12 and has a shape that protrudes sharply while having the curved surface 21b1, so that the discharge path 23 is near the outlet 23b. In FIG. 2, the shape is bent in the opposite direction with respect to the introduction path 22. Other configurations are the same as those in the first embodiment.

Next, the operation for cooling the piston according to the second embodiment will be described.
As described in the first embodiment, when the diesel engine 1 is started, the oil in the circulation unit 11 may flow backward toward the supply unit 12 due to the reciprocating motion of the piston 7. However, the oil flowing backward toward the supply unit 12 flows into the discharge path 23 from the inlet 23a of the discharge path 23 by the guide 21, descends in the discharge path 23, and is discharged from the outlet 23b (arrows F and F). '). At this time, since the surface 21c of the guide 21 protrudes sharply in the horizontal direction while having the concave curved surface 21a1 toward the upper end portion 21a, the oil flowing backward in the circulating portion 11 flows along the curved surface 21a1. This ensures that it flows into the discharge path 23. Further, since the discharge path 23 has a shape bent in the opposite direction to the introduction path 22 in the vicinity of the outlet 23b, the discharge path 23 is ejected upward from the oil jet 15 as indicated by arrows F and F ′. The oil flowing backward is discharged from the outlet 23b so as to be away from the oil.

On the other hand, the newly supplied oil flows into the introduction path 22 and is introduced into the circulation part 11 from the outlet 22b (arrows D and D ′). Since the lower end portion 22a of the introduction path 22 protrudes downward from the opening 12a of the supply portion 12 and the inlet 22a is wider than the outlet 22b, the oil jetted upward from the oil jet 15 is reliably introduced. It flows into the path 22.
Accordingly, the oil ejected upward from the oil jet 15 flows into the introduction path 22, while the oil descending in the discharge path 23 is separated from the oil ejected upward from the oil jet 15 from the outlet 23 b. Since the oil is discharged, the oils are less likely to interfere with each other.

Thus, since the vicinity of the outlet 23b of the discharge path 23 is bent in the opposite direction with respect to the introduction path 22, the oil descending in the discharge path 23 moves away from the oil jetted upward from the oil jet 15. The oil is discharged from the outlet 23b to prevent the oils from interfering with each other.
Further, since the inlet 22a of the introduction path 22 is wider than the outlet 22b, the oil ejected upward from the oil jet 15 can surely flow into the introduction path 22.
Further, since the surface 21c of the guide 21 protrudes sharply in the horizontal direction while having the concave curved surface 21a1 toward the upper end portion 21a, the oil that flows backward from the circulation portion 11 to the supply portion 12 along the curved surface 21a1. The oil that flows and flows backward from the circulation part 11 to the supply part 12 can be reliably introduced into the discharge path 23.

Embodiment 3 FIG.
Next, a piston according to Embodiment 3 of the present invention will be described with reference to FIG.
The piston according to the third embodiment is obtained by changing the shape of the connection portion between the circulation portion 11 and the supply portion 12 of the cooling cavity portion 10 with respect to the first embodiment.
FIG. 5A is a plan view of a connection portion between the circulation portion 11 and the supply portion 12 as viewed from above in the cooling cavity 50 of the piston 7 according to the third embodiment. A circular communication port 24 is formed at a connection portion between the circulation unit 11 and the supply unit 12. Here, in the circulation part 11, the innermost side of the ring formed by the circulation part 11 is an inner circumference 25, and the outermost side of the ring is an outer circumference 26. Around the communication opening 24 of the outer 26 side from the center line L ₁ on the arc at the bottom 11a of the circulating unit 11, the inclined surface 27 of the downward gradient toward the outer periphery 26 side. The inclined surface 27 is formed so as to become wider in the circumferential direction of the circulating portion 11 toward the outer periphery 26 side. Here, the inclined surface 27 constitutes an oil guiding portion for allowing the oil that flows backward from the circulation portion 11 to the supply portion 12 to flow in the supply portion 12 while being biased toward the outer periphery 26 side.

FIG. 5B is a cross-sectional view of the circulation unit 11 and the supply unit 12 along the line Vb-Vb passing through the center of the communication port 24 in FIG. FIG. 5C is a cross-sectional view of the circulation unit 11 and the supply unit 12 taken along line Vc-Vc in contact with the communication port 24 in FIG. FIG. 5 (d) In FIG. 5 (a), a cross-sectional view of the circulating unit 11 and the supply unit 12 along the Vd-Vd line of the outer circumference 26 side from the center line _{L 1.}
FIGS. 5 (b) and 5, as shown in FIG. 5 (c), the cross section of the circulating unit 11 is for a circular inner peripheral 25 side from the center line L _1, the bottom portion 11a toward the center line L ₁ The slope is descending. The outer peripheral 26 side from the center line L _1, the inclined surface 27, and has a downward slope toward the outer 26 side. For this reason, in the periphery of the communication port 24, the bottom portion 11 a has a downward slope from the inner periphery 25 toward the outer periphery 26.
In addition, as shown in FIG. 5D, the inclined surface 27 has a downward slope toward the outer periphery 26 and also has a downward slope toward the supply unit 12.

  Further, the position of the oil jet 15 is adjusted so that the tip 15a (see FIG. 1) of the oil jet 15 is shifted to the inner peripheral 25 side from the center of the supply unit 12.

Next, an operation for cooling the piston according to the third embodiment will be described.
As described in the first embodiment, when the diesel engine 1 is started, the oil in the circulation unit 11 may flow backward to the supply unit 12 due to the reciprocating motion of the piston 7. As shown in FIG. 5 (a), the oil that has flowed back in the circulation section 11 flows along the inclined surface 27 (arrow G), and flows into the supply section 12 while being biased toward the outer periphery 26 side. As a result, the oil that has flowed into the supply section 12 descends in the supply section 12 while being biased toward the outer periphery 26 as indicated by the arrow H in FIG.
On the other hand, the tip 15a (see FIG. 1) of the oil jet 15 is adjusted to a position shifted from the center of the supply unit 12 toward the inner periphery 25, so that the oil jetted upward from the oil jet 15 is As indicated by the arrow I, the inside of the supply unit 12 rises with a bias toward the inner circumference 25 side. Thus, the oil that has flowed back from the circulation unit 11 to the supply unit 12 and the oil that has been newly supplied into the supply unit 12 flow in the supply unit 12 so as to be biased toward the outer periphery 26 side and the inner periphery 25 side, respectively. So that they do not interfere with each other.

  As described above, the bottom portion 11 a is inclined downward from the inner periphery 25 toward the outer periphery 26 around the communication port 24, so that the oil that flows backward from the circulation portion 11 to the supply portion 12 flows inside the supply portion 12. Since the oil newly supplied into the supply unit 12 is lowered toward the inner side 25 in the supply unit 12, the oils are supplied to each other in the supply unit 12. Interference can be prevented.

In the third embodiment, the position of the oil jet 15 is adjusted so that the tip of the oil jet 15 is shifted to the inner circumference 25 side, but such a form is not necessary.
Although the inclined surface 27 is formed to have a downward slope toward the outer periphery 26 side, the present invention is not limited to this. The inclined surface 27 may be formed to have a downward slope toward the inner periphery 25 side. In this case, by providing a range in which the inclined surface 27 is provided around the communication port 24 closer to the inner periphery 25 than the center line L ₁ , the bottom 11 a extends from the outer periphery 26 to the inner periphery around the communication port 24. It is preferable to have a downward slope toward the 25 side. Moreover, you may form the inclined surface 27 so that it may become a downward slope toward both the inner peripheral 25 side and the outer peripheral 26 side.
The range in which the inclined surface 27 is provided and the shape of the inclined surface 27 are not limited to those shown in FIG. 5, and can be appropriately designed according to the use environment and the like.

Further, like the cooling cavity 60 shown in FIG. 6, a V-shaped guide 61 is provided in the supply part 12 of the cooling cavity 50 according to the third embodiment, and the introduction path 22 and the exhaust are discharged in the supply part 12 It may be separated from the path 23. Thereby, in the supply part 12, since the oil which flows backward from the circulation part 11 to the supply part 12 and the oil newly supplied to the supply part 12 distribute | circulate through a separate path | route, each oil can interfere with each other. It can be surely prevented.
In addition, the shape of the guide provided in the supply part 12 is not limited to V shape. It may be two curved guides as in the first embodiment, or may be two guides shaped so that the surfaces of both ends protrude while having concave curved surfaces as in the second embodiment. Good. Further, the vicinity of the outlet 23 b of the discharge path 23 may be bent in the opposite direction with respect to the introduction path 22.

In the third embodiment, the shape of the communication port 24 is circular, but is not limited to this. Like the cooling cavity 70 shown in FIG. 7, the communication port 24 may have a trapezoidal shape. Furthermore, the shape is not limited to a trapezoid, and may be an arbitrary shape such as a quadrangle. In this case, the oil that has flowed back in the circulation unit 11 flows along the inclined surface 27 (arrow J), and flows into the supply unit 12 while being biased toward the outer periphery 26 side.
In the third embodiment, the oil guiding portion is the inclined surface 27, but is not limited to this. A groove communicating with the inner periphery 25 side or the outer periphery 26 side of the communication port 24 may be formed in the bottom portion 11a of the circulation portion 11, and this groove may be used as an oil guiding portion.

Embodiment 4 FIG.
Next, a piston according to Embodiment 4 of the present invention will be described with reference to FIG.
The piston according to the fourth embodiment is obtained by changing the shape of the oil guiding portion with respect to the third embodiment.
FIG. 8A is a plan view of a connection portion between the circulation unit 11 and the supply unit 12 seen from above in the cooling cavity 80 of the piston 7 according to the fourth embodiment. FIG. 8B is a cross-sectional view of the circulation unit 11 and the supply unit 12 along the line VIIIb-VIIIb in contact with the communication port 24 in FIG. So as to be in contact with the communication opening 24, two protrusions 81 are provided on the center line L _1. Here, the convex part 81 comprises an oil guidance part.
The oil flowing backward from the circulation section 11 to the supply section 12 flows into the supply section 12 by being divided into two directions of flow on the inner periphery 25 side and the outer periphery 26 side by the convex portion 81 as indicated by an arrow K. Thereby, the oil which flows backward falls in the supply part 12 in a biased manner toward both the inner circumference 25 side and the outer circumference 26 side. Here, when the position of the oil jet 15 is adjusted such that the tip 15a (see FIG. 1) of the oil jet 15 is positioned at the center of the supply unit 12, the oil jetted upward from the oil jet 15 is indicated by an arrow M. As shown in FIG. 4, it rises through the central part inside the supply part 12. Thereby, in the supply part 12, it can prevent that each oil interferes with each other.

  In the fourth embodiment, only the convex portion 81 that is the oil guiding portion is provided so as to be in contact with the communication port 24, but the present invention is not limited to this. You may provide the inclination which becomes a downward gradient toward the supply part 12 in at least one part of the circumference | surroundings of the convex part 81. FIG.

  In Embodiment 1-4, although the cross section of the circulation part 11 is circular, it is not limited to this, Arbitrary shapes, such as a rectangle, may be sufficient. Moreover, although the circulation part 11 is cyclic | annular, it is not limited to this. It may be partly divided.

  DESCRIPTION OF SYMBOLS 1 Diesel engine (internal combustion engine), 7 piston, 10, 30, 40, 50, 60, 70, 80 Cooling cavity part, 11 Circulation part (annular cylindrical tube), 11a Bottom of circulation part 11, 12 Supply part, 12a Opening (of supply part 12) 21,30 Guide, 21a (Upper part of guide 21), 21b Lower end part of (Guide 21), 21a1, 21b1 Curved surface, 21c Surface of (Guide 21), 22 Introduction path, 22a (Introduction path 22) Inlet, 22b Outlet (Introduction path 22), 23 Discharge path, 23a (Discharge path 23) Inlet, 23b (Discharge path 23) Outlet, 24 Communication port, 25 (Circulation section 11) ) Inner circumference, 26 Outer circumference (of the circulation part 11), 27 Inclined surface (oil guiding part), 81 Convex part (oil guiding part)

Claims (6)

A piston that moves up and down in a cylinder provided inside a cylinder block of an internal combustion engine,
An annular cylindrical tube formed in the piston;
A supply unit that communicates with the annular cylindrical tube and is supplied with the oil;
In a piston comprising a cooling cavity that communicates with the annular cylindrical tube and has a discharge portion through which the oil that has flowed through the annular cylindrical tube is discharged,
The oil is supplied from the oil jet provided in the cylinder block toward the supply unit, whereby the oil is supplied to the supply unit,
The supply unit
An introduction path through which oil supplied to the supply unit is introduced into the annular cylindrical tube;
A piston, comprising: a discharge path that is provided adjacent to the introduction path by being separated by a guide, and that discharges oil that flows backward in the annular cylindrical tube toward the supply section.   The piston according to claim 1, wherein the guide is formed in a plate shape and extends to the inside of the annular cylindrical tube.   The piston according to claim 2, wherein a length of the guide in the annular cylindrical tube is 1/2 to 2/3 of an inner diameter of the annular cylindrical tube.   4. The piston according to claim 2, wherein a surface of the guide facing the discharge path projects in an opposite direction to the introduction path toward the upper end portion.   The piston according to any one of claims 2 to 4, wherein an inlet of the introduction path is wider than an outlet of the introduction path. The surface of the guide facing the discharge path protrudes in the opposite direction with respect to the introduction path toward the lower end.
The piston according to any one of claims 2 to 5, wherein a vicinity of an outlet of the discharge path is bent in a direction opposite to the introduction path.

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