JP2021017866A - Piston for internal combustion engine - Google Patents

Abstract

To provide a piston for an internal combustion engine which enables oil to be supplied smoothly to a slide part between an outer peripheral surface of the piston and an inner peripheral surface of a cylinder.SOLUTION: A piston 10 for an internal combustion engine in which piston skirts 14a, 14b are extended downward from a piston head 13 includes oil guide members 18a, 18b having, at the inner side of the piston skirts 14a, 14b, oil receiving parts 19a, 19b which receive oil L jetted to a lower surface of the piston head 13 and oil feed parts 20a, 20b which guide the oil L from the lower end side of the piston skirts 14a, 14b to an inner peripheral surface of the cylinder 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to pistons for internal combustion engines of vehicles.

A piston for an internal combustion engine for a vehicle (hereinafter referred to as a piston) reciprocates in a cylinder formed in an engine block in the vertical direction of the vehicle body. Oil (engine oil) is supplied between the outer peripheral surface of the piston and the inner peripheral surface (liner) of the cylinder. This oil lubricates and cools the outer peripheral surface of the piston and the inner peripheral surface of the cylinder.

In order to properly maintain the lubrication state by oil between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder, for example, in Patent Document 1, a communication hole 113 extending from the inner surface to the outer peripheral surface of the piston 11 is formed in the piston skirt. ing. Then, the oil that has passed through the connecting rod oil flow path 133 formed in the connecting rod 13 is supplied to the surface of the piston 11 from the communication hole 113 (see paragraphs 0009 to 0013 of Patent Document 1, FIG. 1 and the like). ..

Further, in Patent Document 2, communication holes 30 and 31 for communicating the inside of the oil ring groove 29 and the inside of the piston 8 are formed corresponding to the portions where the skirt portions 21 and 22 of the oil ring groove 29 are located. There is. Then, the oil injected from the nozzle 15 into the piston 8 is supplied to the oil ring groove 29 side through the communication holes 30 and 31 (paragraph 0021 of Patent Document 2, FIGS. 1, 3, 3). See 4th grade).

Further, in Patent Document 3, an oil storage recess 4 is formed on the outer peripheral surface of the skirt along the circumferential direction, and a through hole 5 penetrating the inside of the piston is formed in the oil storage recess 4. .. Then, in the descending stroke of the piston 3, excess oil 7 is collected in the oil reservoir recess 4 and discharged to the inside of the piston 3 through the through hole 5 (paragraphs 0029 to 0031 of Patent Document 3, FIG. 2). Etc.).

Further, in Patent Document 4, a protruding portion 40 projecting inward in the radial direction is formed on the inner peripheral surface 38 of the lower end portion of the skirt portion 34. Then, the oil that flows downward along the inner peripheral surface 38 of the skirt portion 34 is turned inward in the radial direction of the piston by the protrusion 40 so as to be separated from the inner peripheral surface 38 of the skirt portion 40. The oil is suppressed from being transmitted to the inner peripheral surface side of the cylinder 11 (see paragraphs 0020 to 0023 of Patent Document 4, FIG. 3 and the like).

Japanese Unexamined Patent Publication No. 9-60725 JP-A-2010-150994 Japanese Unexamined Patent Publication No. 2004-225596 JP-A-2015-206295

In the configurations shown in Patent Documents 1 to 3, oil is supplied and discharged from the inner peripheral surface to the outer peripheral surface of the piston or from the outer peripheral surface to the inner peripheral surface by forming a through hole in the piston skirt. , There is a problem that it is difficult to secure a sufficient flow rate of oil in the through holes having a relatively small diameter shown in each patent document. Although it is possible to secure the flow rate of oil by increasing the diameter of this through hole, forming a large through hole in the piston skirt of the piston on which a large force acts when the engine is driven ensures the strength of the piston. It is not preferable from the viewpoint of. Further, the configuration shown in Patent Document 4 may further reduce the amount of oil supplied to the outer peripheral surface of the piston, which is originally difficult to lubricate, and is not preferable in terms of ensuring lubricity.

Therefore, an object of the present invention is to smoothly supply oil to a sliding portion between an outer peripheral surface of a piston and an inner peripheral surface of a cylinder.

In order to solve the above problems, in the present invention, in the piston for an internal combustion engine in which the piston skirt extends downward from the piston head, the piston is injected inside the piston skirt toward the lower surface of the piston head. The piston for an internal combustion engine is configured to include an oil receiving portion for receiving oil and an oil guiding member having an oil feeding portion for guiding oil from the lower end side of the piston skirt to the inner peripheral surface of the cylinder.

In the above configuration, the lower end of the oil feeding portion may have an oil collecting portion formed of a recess that opens toward the inner peripheral surface of the cylinder and can store oil.

In the configuration having the oil sump portion, the cylinder extends from the lower end of the piston skirt so as to face the upper side of the oil sump portion, and the oil splashed from the oil sump portion as the piston moves up and down. It can be configured to have an extension portion that bounces toward the inner peripheral surface of the.

In the configuration having the extension portion, the oil sump portion and the extension portion are individually formed on both the thrust side and the non-thrust side of the cylinder, and the capacity of the oil sump portion, Alternatively, at least one of the sizes of the gap between the oil pool portion and the extension portion may be larger on the thrust side than on the non-thrust side.

In each of the above configurations, the oil receiving portion is individually formed on both the thrust side and the non-thrust side of the cylinder, and the area of the oil receiving portion is closer to the thrust side than the non-thrust side. It can be a large configuration.

The piston for an internal combustion engine according to the present invention has an oil receiving portion inside the piston skirt that receives oil injected toward the lower surface of the piston head, and oil on the inner peripheral surface of the cylinder from the lower end side of the piston skirt. Since it is provided with an oil guiding member having an oil feeding portion that guides the piston skirt, the outer peripheral surface of the piston and the inner peripheral surface of the cylinder are formed from the lower end side of the piston skirt without forming a through hole for passing oil through the piston skirt. A sufficient amount of oil can be smoothly supplied to the sliding portion between the two.

It is sectional drawing which shows one Embodiment of the piston for an internal combustion engine which concerns on this invention. It is sectional drawing which follows the line II-II in FIG. It is sectional drawing which shows the main part of FIG. 1, (a) shows a thrust side, (b) shows a non-thrust side. It is sectional drawing which shows the operation of the piston for an internal combustion engine shown in FIG. It is sectional drawing which shows the operation of the piston for an internal combustion engine shown in FIG. 1, (a) shows a steady drive of an engine, and (b) shows just after the engine start.

An embodiment of a piston 10 for an internal combustion engine (hereinafter, referred to as a piston 10) according to the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 3, the piston 10 reciprocates in the cylinder 12 formed in the cylinder block 11 of the internal combustion engine for a vehicle (hereinafter referred to as an engine) in the vehicle body vertical direction. It is provided so that it can be moved. The piston 10 is a pair of a piston head 13 forming a combustion chamber with a cylinder head (not shown) and a pair of piston heads 13 extending downward from the outer peripheral edge of the piston head 13 and facing each other in the radial direction. It has piston skirts 14a and 14b.

The piston 10 according to this embodiment is used in an engine slanted (slant angle θ) on the thrust side of the cylinder 12. One piston skirt 14a is located on the thrust side (left side in FIG. 1), and the other piston skirt 14b is located on the non-thrust side (right side in FIG. 1). A piston clearance g having a predetermined size is formed between the outer peripheral surfaces of the piston head 13 and the piston skirts 14a and 14b and the inner peripheral surface (liner) of the cylinder 12. By supplying oil to the piston clearance g, the space between the piston 10 and the cylinder 12 is lubricated.

Piston bosses 15 having pin holes formed are continuously provided on the lower surface of the piston head 13. A piston pin 16 is inserted through this pin hole. A small-diameter end of a connecting rod 17 that moves the piston 10 up and down is connected to the piston pin 16. As will be described later, oil L (see FIG. 4) is injected upward from the large diameter end side (not shown) of the connecting rod 17 onto the lower surface of the piston head 13. The injected oil L once adheres to the lower surface of the piston head 13, and then gradually drops from the lower surface.

Oil guiding members 18a and 18b are provided on the lower surface side of the piston head 13. The oil guiding members 18a and 18b are injected toward the lower surface of the piston head 13, and the oil L dropped from the lower surface is guided from the lower end side of the piston skirts 14a and 14b to the inner peripheral surface of the cylinder 12.

The oil guiding members 18a and 18b have oil receiving portions 19a and 19b, oil feeding portions 20a and 20b, and oil collecting portions 21a and 21b. The oil guide members 18a and 18b correspond to the formation positions of the piston skirts 14a and 14b and are individually on the thrust side and the non-thrust side of the cylinder 12 (oil guide members 18a on the thrust side and oil on the non-thrust side). Guidance member 18b) is provided.

The oil receiving portions 19a and 19b are members having a substantially horizontal upper surface and partially formed with circular through holes 22a and 22b to receive the oil L dripping from the lower surface of the cylinder head 13. The peripheral edges of the through holes 20a and 20b project upward so as to face the lower surface of the piston head 13, and the diameter thereof decreases toward the upper side. A gap is provided between the upper ends of the through holes 20a and 20b and the lower surface of the piston head 13 so that oil can flow along the lower surface of the piston head 13. The opening diameters of the through holes 20a and 20b are substantially the same on the thrust side and the non-thrust side.

The circumferential width of the oil receiving portions 19a and 19b in the direction along the outer peripheral surface of the piston 10 is substantially the same as the circumferential width of the piston skirts 14a and 14b. Further, the positions of the outer diameter side ends of the pistons 10 of the oil receiving portions 19a and 19b are the same on both the thrust side and the non-thrust side, but the thrust side is the outer diameter position of the piston boss 15 at the inner diameter side ends. On the other hand, the non-thrust side is the piston inner diameter position of the through hole 22b. That is, the area of the oil receiving portions 19a and 19b (projected area on the horizontal plane) is larger on the thrust side than on the non-thrust side, and more oil L dripping from the lower surface of the cylinder head 13 can be received on this thrust side. It is configured so that it can be done.

The oil receiving portion 19b on the non-thrust side is provided with a partition wall 23 extending from the receiving surface of the oil receiving portion 19b to the lower surface of the cylinder head 13. The partition wall 23 prevents the oil L that has passed through the through hole 22b from flowing to the thrust side, so that in an engine slanted to the thrust side, the oil L is relatively difficult to spread on the non-thrust side as compared with the thrust side. A sufficient amount of oil is secured.

The oil feeding portions 20a and 20b are members connected downward from the outer peripheral side of the oil receiving portions 19a and 19b and feed the oil L received by the oil receiving portions 19a and 19b to the vicinity of the lower ends of the piston skirts 14a and 14b. ..

The oil collecting portions 21a and 21b have recesses that open toward the inner peripheral surface of the cylinder 12, and flow downward along the oil feeding portions 20a and 20b that are continuously provided at the lower ends of the oil feeding portions 20a and 20b. It is a member that temporarily stores the oil L. The oil sump portions 21a and 21b are formed so as to correspond to the entire lower ends of the piston skirts 14a and 14b in the circumferential direction thereof.

At the lower ends of the piston skirts 14a and 14b, extending portions 24a and 24b bent inward in the radial direction of the piston 10 so as to face the upper side of the oil collecting portions 21a and 21b are formed in the entire circumferential direction of the piston skirts 14a and 14b. It is continuously installed over. The extending portions 24a and 24b are members that bounce the oil L that has jumped up from the oil collecting portions 21a and 21b toward the inner peripheral surface of the cylinder 12 as the piston 10 moves up and down. Gap g ₁ and g ₂ having predetermined sizes are formed between the oil pool portions 21a and 21b and the extension portions 24a and 24b.

The capacity of the oil sump portion 21a on the thrust side is larger than the capacity of the oil sump portion 21b on the non-thrust side. When the piston 10 descends with combustion, a relatively large thrust force (friction force between the piston 10 and the cylinder 12) acts on the thrust side as compared with the non-thrust side. Therefore, by increasing the capacity of the oil sump portion 21a on the thrust side as compared with the non-thrust side, more oil L can be supplied to the thrust side, and a sufficient lubrication state on the thrust side can be ensured. ..

The size of the gap g ₁ between the oil reservoir 21a on the thrust side and the extension portion 24a is larger than the size of the gap g ₂ between the oil reservoir 21b on the non-thrust side and the extension portion 24b. By making the gap g ₁ on the thrust side larger than the gap g ₂ on the non-thrust side in this way, the oil L stored in the oil pool portion 21a can be more smoothly sent to the inner peripheral surface of the cylinder 12. , As described above, a sufficient lubrication state on the thrust side can be ensured.

Three peripheral grooves are formed on the outer peripheral surface of the piston head 13. The upper two peripheral grooves have compression rings 25 and 25 for maintaining the airtightness of the combustion chamber, and the lowermost peripheral groove has an oil ring 26 for forming an appropriate oil film on the inner peripheral surface of the cylinder 12. Are provided respectively.

The operation of the oil guiding member 18a will be described with reference to FIG. The oil L injected upward from the large-diameter end side of the connecting rod 17 (see FIG. 1) passes through the through hole 22a formed in the oil receiving portion 19a and adheres to the lower surface of the piston head 13. Then, the oil L spreads laterally on the lower surface of the piston head 13 and drops from the lower surface. The dropped oil L is received by the oil receiving portion 19a. The received oil L flows downward along the oil feeding portion 20a. The oil L that has flowed down is temporarily stored by the oil pool portion 21a.

As shown in FIG. 5A, during the steady drive of the engine, the oil L continuously flows down from the oil receiving portion 19a and the oil feeding portion 20a to the oil collecting portion 21a, and overflows from the oil collecting portion 21a. The oil L is supplied to the inner peripheral surface of the cylinder 12.

On the other hand, as shown in FIG. 5B, immediately after the engine is started, the oil L has not yet flowed down from the oil receiving portion 19a and the oil feeding portion 20a to the oil collecting portion 21a, but to the oil collecting portion 21a. Is a state in which the oil L accumulated during the previous engine drive remains. When the engine is started in this state, the oil L accumulated in the oil sump portion 21a jumps up as the piston 10 (see FIG. 1) moves upward (see the white arrow in FIG. 5 (b)), and the oil L jumps up. Is bounced off the inner peripheral surface of the cylinder 12 by the extension portion 24a. As a result, oil is supplied to the inner peripheral surface of the cylinder 12 immediately after the engine is started.

In FIGS. 5A and 5B, the action of the oil guiding member 18a on the thrust side is shown, but the action of the oil guiding member 18b on the non-thrust side is the same as this.

The above embodiment is merely an example, and as long as the problem of the present invention of smoothly supplying the oil L to the sliding portion between the outer peripheral surface of the piston 10 and the inner peripheral surface of the cylinder 12 can be solved. The configuration described above can be modified as appropriate.

For example, in the above embodiment, the configuration in which the circular through holes 22a and 22b are formed in the oil receiving portions 19a and 19b has been described, but the shapes of the through holes 22a and 22b are not limited to this. Further, instead of forming the through holes 22a and 22b, a gap having a size capable of passing the oil L injected from the lower side of the oil receiving portions 19a and 19b toward the lower surface side of the piston head 13 is formed. You may.

Further, in the above embodiment, the oil L is temporarily stored by the oil reservoirs 21a and 21b, but the oil L is temporarily stored through the oil feed portions 20a and 20b without forming the oil reservoirs 21a and 21b. The oil L that has flowed down may be directly supplied to the inner peripheral surface of the cylinder 12.

Further, in the above embodiment, in the thrust side than non-thrust side, the capacity of the oil reservoir 21a, and, the configuration to increase neither the gap g ₁ between the oil reservoir 21a and the extending portion 24a However, for example, the capacity is the same on the thrust side and the non-thrust side, but only the size of the gap g ₁ is increased on the thrust side, or the gap g ₁ and g on the thrust side and the non-thrust side. _While the size of ₂ is the same, only the capacity may be increased on the thrust side.

Further, in the above embodiment, the oil L is supplied to the lower surface side of the piston head 13 from the large diameter end side of the connecting rod 17, but the oil L is injected from the small diameter end side of the connecting rod 17. The supply source of the oil L to the lower surface side of the piston head 13 is not particularly limited, for example, the oil injection nozzle for injecting the oil L is provided on the lower surface side of the piston head 13.

Further, in the above embodiment, an example of application to an engine slanted on the thrust side has been described, but it can also be applied to an engine not slanted. When the engine is not slanted, the partition wall 23 provided on the oil guiding member 18b on the non-thrust side can be omitted.

10 Piston 11 Cylinder block 12 Cylinder 13 Piston head 14a, 14b Piston skirt 15 Piston boss 16 Piston pin 17 Connecting rod 18a, 18b Oil guiding member 19a, 19b Oil receiving part 20a, 20b Oil feeding part 21a, 21b Oil collecting part 22a, 22b Through hole 23 Partition 24a, 24b Extension 25 Compression ring 26 Oil ring

Claims (5)

In a piston for an internal combustion engine in which a piston skirt extends downward from the piston head.
An oil guiding member having an oil receiving portion for receiving oil injected toward the lower surface of the piston head and an oil feeding portion for guiding oil from the lower end side of the piston skirt to the inner peripheral surface of the cylinder inside the piston skirt. A piston for an internal combustion engine, which is characterized by being equipped with. The piston for an internal combustion engine according to claim 1, further comprising an oil reservoir portion at the lower end of the oil feed portion, which is open toward the inner peripheral surface of the cylinder and is formed of a recess capable of accumulating oil. An extension extending to the lower end of the piston skirt so as to face the upper side of the oil reservoir, and repelling the oil splashed from the oil reservoir as the piston moves up and down toward the inner peripheral surface of the cylinder. The piston for an internal combustion engine according to claim 2, which has a portion. The oil sump portion and the extension portion are individually formed on both the thrust side and the non-thrust side of the cylinder, and the capacity of the oil sump portion or the oil sump portion and the extension portion are formed. The piston for an internal combustion engine according to claim 3, wherein at least one of the sizes of the gaps between the portions is larger on the thrust side than on the non-thrust side. Claims 1 to 4 in which the oil receiving portion is individually formed on both the thrust side and the non-thrust side of the cylinder, and the area of the oil receiving portion is larger on the thrust side than on the non-thrust side. The piston for an internal combustion engine according to any one of the above items.

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