JP2019199844A - Piston for internal combustion engine - Google Patents

Abstract

To suppress degradation of an oil scraping function on an inner wall surface of a cylinder.SOLUTION: A piston 20 for an internal combustion engine includes a piston main body portion 21 on which a through hole 24a penetrating through an outer peripheral surface 21a and an inner peripheral surface 21b is formed, and a passage portion 25 communicated with an inner peripheral surface 21b side of the piston main body portion 21 in the through hole 24a at one end 25a, opened at the other end 25b, and extended from one end 25a to the other end 25b in a direction separating from a crown surface 20a, and a direction approaching the piston main body portion 21 in an axis L direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a piston for an internal combustion engine.

  Conventionally, a piston for an internal combustion engine has a through hole (oil return hole) for allowing excess oil on the inner wall surface of the cylinder to escape to the inside of the piston in the oil ring groove (for example, Patent Document 1).

JP-A-7-139423

  However, when the opening inside the piston in the through hole formed in the oil ring groove is submerged, there is a problem that excess oil on the inner wall surface of the cylinder cannot be scraped into the piston.

  Then, an object of this invention is to provide the piston for internal combustion engines which can suppress that the scraping function of the oil in a cylinder inner wall surface falls.

  In order to solve the above-described problems, a piston for an internal combustion engine according to the present invention includes a piston main body portion in which a through hole penetrating an outer peripheral surface and an inner peripheral surface is formed, and an inner peripheral surface side of the piston main body portion in the through hole One end communicates with the other end, the other end is open, a passage portion extending from one end to the other end in a direction away from the crown surface and in a direction close to the axial direction of the piston main body, Is provided.

  In addition, a piston boss part is provided which is continuously provided in the piston main body part and formed with a piston pin hole into which a piston pin for connecting the connecting rod is inserted, and the passage part is provided vertically below the piston boss part. It should be done.

  Further, the other end of the passage portion may be located in the vicinity of the piston boss portion.

  The passage portion may be formed in a plate-like rib provided on the inner peripheral surface side of the piston main body portion.

  Moreover, it is good for a through-hole to be formed in the ring groove formed in the outer peripheral surface of a piston main-body part.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress that the oil scraping function in the inner wall face of a cylinder falls.

It is a figure for demonstrating the structure of the engine provided with the piston. It is a figure for demonstrating sectional drawing of a piston. It is a figure for demonstrating the right view of a piston.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram illustrating a configuration of an engine 1 including a piston 20. In the following, the traveling direction of the vehicle is the forward direction, the backward direction of the vehicle is the backward direction, the right side with respect to the traveling direction of the vehicle is the right direction, the left side with respect to the traveling direction of the vehicle is the left direction, and the vertical upward direction is the upward direction. The direction and the vertically downward direction will be described as the downward direction. Further, in FIG. 1, the cylinder 5 in the left direction and the vicinity thereof are shown in cross section for easy understanding.

  As shown in FIG. 1, the engine 1 is a horizontally opposed engine in which, for example, cylinders are horizontally disposed with a crankshaft 9 interposed therebetween. The engine 1 includes a cylinder block 2, a crankcase 3 integrally formed with the cylinder block 2, and a cylinder head 4 fixed to the cylinder block 2.

  A piston 20 is slidably disposed in a cylinder 5 formed in the cylinder block 2. The piston 20 is supported by the connecting rod 6. In the engine 1, a space surrounded by the cylinder head 4, the cylinder 5, and the crown surface 20 a of the piston 20 is formed as the combustion chamber 7.

  A crankshaft 9 is rotatably supported in a crank chamber 8 formed by the crankcase 3. The connecting rod 6 is rotatably supported on the crankshaft 9. As a result, the piston 20 is connected to the crankshaft 9 via the connecting rod 6.

  An intake port 10 and an exhaust port 11 are formed in the cylinder head 4 so as to communicate with the combustion chamber 7. The intake port 10 has one opening on the upstream side of the intake air and two openings on the downstream side of the intake air facing the combustion chamber 7, and the flow path branches into two on the way from the upstream to the downstream. Is done.

  The exhaust port 11 is formed with two openings on the upstream side of the exhaust facing the combustion chamber 7 and one opening on the downstream side of the exhaust, and the flow path merges into one on the way from the upstream to the downstream. To do.

  An umbrella portion of the intake valve 12 is located between the intake port 10 and the combustion chamber 7, and an umbrella portion of the exhaust valve 13 is located between the exhaust port 11 and the combustion chamber 7. An intake camshaft 14 to which a cam 14a is fixed and an exhaust camshaft 15 to which a cam 15a is fixed are provided in a cam chamber surrounded by the cylinder head 4 and a head cover (not shown). The intake camshaft 14 and the exhaust camshaft 15 are connected to the crankshaft 9 via a timing chain, and rotate as the crankshaft 9 rotates.

  The cam 14 a is in contact with the shaft end of the intake valve 12, and is rotated by the intake camshaft 14 to move the intake valve 12 in the axial direction. Thereby, the intake valve 12 opens and closes between the intake port 10 and the combustion chamber 7. The cam 15a is in contact with the end of the exhaust valve 13 and is rotated by the exhaust camshaft 15 to move the exhaust valve 13 in the axial direction. Thereby, the exhaust valve 13 opens and closes between the exhaust port 11 and the combustion chamber 7.

  The cylinder head 4 is provided with a spark plug (not shown) so that the tip is located in the combustion chamber 7, and the air-fuel mixture flowing into the combustion chamber 7 through the intake port 10 is a predetermined mixture. At this timing, the spark plug is ignited and burned. Due to such combustion, the piston 20 reciprocates in the cylinder 5, and the reciprocating motion is converted into rotational motion of the crankshaft 9 through the connecting rod 6.

  Three ring grooves 27, 28, 29 that are recessed in the radial direction of the piston main body 21 are formed on the outer peripheral surface 21 a of the piston main body 21 of the piston 20 in order from the crown surface 20 a side. The ring grooves 27, 28, and 29 are formed along the circumferential direction of the piston main body 21. The ring grooves 27, 28, and 29 are provided near the crown surface 20 a on the outer peripheral surface 21 a of the piston main body 21.

  A top ring 37 is accommodated in the ring groove 27. A second ring 38 is accommodated in the ring groove 28. An oil ring 39 is accommodated in the ring groove 29.

  The top ring 37, the second ring 38, and the oil ring 39 protrude in the radial direction from the outer peripheral surface 21 a of the piston main body 21 while being accommodated in the ring grooves 27, 28, and 29, and come into contact with the cylinder 5. The top ring 37 and the second ring 38 eliminate the gap between the cylinder 5 and the side surface of the piston main body 21 and keep the combustion chamber 7 airtight. The oil ring 39 scrapes off excess oil on the inner wall surface of the cylinder 5 to form an appropriate oil film between the cylinder 5 and the outer peripheral surface 21a of the piston main body 21 to lubricate the sliding of the piston main body 21. To do.

  FIG. 2 is a view for explaining a sectional view of the piston 20. FIG. 3 is a view for explaining a right side view of the piston 20. As shown in FIG. 2, the piston 20 is provided with a piston main body 21 formed in a bottomed cylindrical shape having a space formed therein. In the internal space of the piston main body 21, a piston boss 23 is provided continuously to the piston main body 21. A piston pin hole 22 for connecting the piston 20 and the connecting rod 6 is formed in the piston boss portion 23 along a direction orthogonal to the central axis of the piston main body portion 21.

  The ring groove 29 is provided with through holes 24 a and 24 b that penetrate the outer peripheral surface 21 a and the inner peripheral surface 21 b of the piston main body 21. The number and arrangement of the through holes 24a and 24b are set so as to obtain a desired oil scraping function.

  Specifically, as shown in FIG. 3, four through holes 24b are provided vertically above the piston boss portion 23 so as to face the upper surface 23b of the piston boss portion 23 with a predetermined interval therebetween. ing. And the through-hole 24b has the opening part 31a opened to the outer peripheral surface 21a of the piston main-body part 21, and the opening part 31b opened to the internal peripheral surface 21b.

  Further, four through holes 24a are provided at predetermined intervals below the piston boss portion 23 so as to face the lower surface 23a of the piston boss portion 23. The through hole 24 a has an opening 30 that opens to the outer peripheral surface 21 a of the piston main body 21.

  Further, a plate-like rib 26 is provided on the inner peripheral surface 21 b side of the piston main body portion 21 and on the lower surface 23 a side of the piston boss portion 23. The rib 26 is provided so as to contact the lower surface 23 a of the piston main body 21 and the piston boss 23. Further, as shown in FIG. 3, two ribs 26 are provided. The two ribs 26 are symmetrically disposed on the front side and the rear side of the vehicle, respectively.

  In addition, two passage portions 25 are formed in the rib 26, respectively. And the four through-holes 24a and the four channel | path parts 25 are each paired, and the through-hole 24a and the channel | path part 25 which are used as a pair are connecting. As shown in FIG. 2, the passage portion 25 has one end 25 a communicating with the inner peripheral surface 21 b side of the piston main body portion 21 in the through hole 24 a. Moreover, the channel | path part 25 is extended linearly toward the upper right from the one end 25a. In other words, the passage portion 25 extends from the one end 25a to the other end 25b (opening 32) in a direction away from the crown surface 20a and in a direction close to the axis L direction of the piston main body portion 21. ing. The other end 25 b (opening 32) of the passage portion 25 is open in the vicinity of the piston boss portion 23. The opening 32 of the passage portion 25 functions as an oil outlet on the inner wall surface of the cylinder 5 scraped out by the oil ring 39.

  As shown in FIG. 2, a notch 26 a is formed in the lower right portion of the rib 26 so as to be inclined vertically upward of the piston boss portion 23 as the distance from the crown surface 20 a increases. The notch 26 a is provided to reduce the weight of the rib 26. Further, a notch 26b is formed at the upper right portion of the rib 26 so as to be inclined vertically downward of the piston boss portion 23 as the distance from the crown surface 20a increases. The notch 26b is provided to prevent the connecting rod 6 and the rib 26 from interfering when the engine 1 is driven. Moreover, the opening part 32 of the channel | path part 25 is arrange | positioned on the notch 26b. Therefore, oil can be efficiently discharged from the opening 32 of the passage portion 25 along the inclination of the notch 26b.

  By the way, in the engine 1, when the vehicle turns, the oil may be biased by centrifugal force. The position of the oil surface varies depending on the amount of oil in an oil pan (not shown) and the magnitude of centrifugal force acting on the vehicle. For example, when a centrifugal force in the left direction is applied to the vehicle, the oil level of the oil may be located on the dotted line S shown in FIG. In such a case, if the rib 26 is not provided, the through hole 24a located vertically below the piston boss portion 23 will be immersed in oil. For this reason, oil that has excessively adhered to the inner wall surface of the cylinder 5 cannot be discharged into the piston 20 through the through hole 24a, and excess oil remains on the inner wall surface of the cylinder 5.

  On the other hand, in the piston 20 of the present embodiment, even when the oil is biased by the centrifugal force and the oil level is located on the dotted line S, the opening 32 of the passage 25 is higher than the oil level. Will be located. Therefore, the oil outlet (opening 32 of the passage portion 25) on the inner wall surface of the cylinder 5 that the oil ring 39 has scraped can be prevented from being immersed in oil. Thereby, it can suppress that the scraping function of the oil in the inner wall face of the cylinder 5 falls. In addition, this prevents the remaining oil from remaining on the inner wall surface of the cylinder 5, thereby reducing the remaining oil from burning. As a result, an increase in oil consumption can be reduced. On the other hand, on the upper surface 23b side of the piston boss portion 23, since there is little possibility that the through hole 24b is immersed in oil, the passage portion 25 and the rib 26 are not provided, so that the weight of the piston 20 can be reduced.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  The ribs 26 may be formed by casting so as to be integrated with the piston main body 21, or a member prepared separately from the piston main body 21 may be attached by welding or the like. For example, in the above-described embodiment, the case where the two passage portions 25 are provided so as to share one rib 26 is described, but the rib 26 may be provided for each passage portion 25. However, since the plurality of passage portions 25 share one rib 26, the number of parts can be reduced as compared with the case where the rib 26 and the piston main body 21 are prepared separately.

  Moreover, although embodiment mentioned above demonstrated the case where the channel | path part 25 was provided in the rib 26, this invention is not limited to this. That is, the opening portion 32 of the passage portion 25 only needs to function as an oil outlet on the inner wall surface of the cylinder 5 raked out by the oil ring 39. For example, the opening portion 32 of the passage portion 25 may be formed of a cylindrical member provided with the passage portion 25. Good. At this time, it is preferable to arrange four cylindrical members so as to correspond to each of the through holes 24a. The cylindrical member is preferably inclined so as to be directed vertically upward as it is separated from the crown surface 20a. The shape of the cylindrical member may be a columnar shape or a prismatic shape.

  In the above-described embodiment, the case where the piston 20 is provided with the through hole 24b so as to face the upper surface 23b of the piston boss portion 23 is described, but the through hole 24b may not be provided. In other words, the through hole only needs to be provided at least at a place where oil is likely to accumulate in the cylinder due to gravity and a place where the oil level may reach when the vehicle turns.

  In the above-described embodiment, the case where the passage portion 25 and the rib 26 are provided only on the lower surface 23a side of the piston boss portion 23 has been described, but the passage portion 25 and the rib are also provided on the upper surface 23b side of the piston boss portion 23. 26 may be provided.

  In the above-described embodiment, the case where the engine 1 is a horizontally opposed engine has been described. However, the engine 1 is not limited to a horizontally opposed engine.

  The present invention can be used for a piston for an internal combustion engine.

6 Connecting rod 20 Piston 21 Piston body part 23 Piston boss part 24a Through hole 25 Passage part 26 Rib 29 Ring groove

Claims (5)

A piston main body formed with a through-hole penetrating the outer peripheral surface and the inner peripheral surface;
One end is connected to the inner peripheral surface side of the piston main body portion in the through hole, the other end is opened, and the piston main body is in a direction away from the crown surface from the one end to the other end. A passage portion extending in a direction close to the axial direction of the portion;
A piston for an internal combustion engine comprising: A piston boss part formed continuously with the piston main body part and having a piston pin hole into which a piston pin for connecting a connecting rod is inserted;
The piston for an internal combustion engine according to claim 1, wherein the passage portion is provided vertically below the piston boss portion.   The piston for an internal combustion engine according to claim 2, wherein the other end of the passage portion is located in the vicinity of the piston boss portion.   The piston for an internal combustion engine according to any one of claims 1 to 3, wherein the passage portion is formed in a plate-like rib provided on the inner peripheral surface side of the piston main body portion.   The piston for an internal combustion engine according to any one of claims 1 to 4, wherein the through hole is formed in a ring groove formed on an outer peripheral surface of the piston main body.

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