JP5304187B2 - Double link piston crank mechanism for internal combustion engine - Google Patents

Description

  The present invention relates to a multi-link piston crank mechanism for a reciprocating internal combustion engine.

As a prior art in which a piston pin and a crank pin of a reciprocating internal combustion engine are connected by a multi-link type piston crank mechanism, Patent Document 1 previously proposed by the present applicant is known. This includes an upper link connected to the piston pin of the piston, a lower link connecting the upper link and the crank pin of the crankshaft, one end supported to be swingable to the engine body side, and the other end to the lower link. A control link coupled to the link. The upper link and the lower link are rotatably connected to each other via an upper pin, and the control link and the lower link are rotatably connected to each other via a control pin.
JP 2004-1224776 A

  In such a multi-link type piston crank mechanism, a large maximum combustion pressure received by the piston in the vicinity of the top dead center of the piston is input to the upper pin bearing portion of the lower link via the piston pin, the upper link, and the upper pin. A load is also generated in the crank pin bearing portion and the control pin bearing portion so that the load and the inertial force are balanced. Accordingly, the surface pressure of each bearing portion is stricter than that of a general single link type reciprocating engine, and it is required to maintain a sufficient lubrication state in order to prevent wear and seizure. In particular, it is difficult to supply sufficient lubricating oil to the bearing portion of the upper pin and the control pin because it cannot be supplied directly through the inner passage of the crankshaft like the crankpin bearing portion. Maintaining performance is difficult. In addition, it is required to achieve both support rigidity and compactness while ensuring such lubrication performance.

  A multi-link type piston crank mechanism for an internal combustion engine according to the present invention includes an upper link having one end connected to a piston via a piston pin, and connected to the other end of the upper link via an upper pin, and a crankshaft crank A lower link coupled to the pin, and a control link having one end pivotably supported on the engine body side and the other end coupled to the lower link via a control pin. At least one of the upper link and the control link has a cylindrical pin boss portion into which the upper pin or the control pin is rotatably fitted, and a rod portion integrally connected to the pin boss portion. . The rod portion has a pair of first side surfaces that are continuous with the side surfaces of the pin boss portion, and a pair of second side surfaces that are continuous with the outer peripheral surface of the pin boss portion. It is characterized in that it has a cross-sectional H shape in which an extending concave groove is formed.

  Compared with the comparative example in which the concave groove is formed on the first side surface connected to the side surface of the pin boss portion because the concave groove is formed on the second side surface continuous to the outer peripheral surface of the pin boss portion, the cross section in the crank rotation direction The shape is excellent in rigidity against the second moment, and the thickness of the rod portion in the crankshaft direction can be reduced. By thinning the rod part in the axial direction, the groove width of the interference avoidance groove with the rod part formed on the lower link is reduced, and the ribs on both sides are made thicker. The bending strength around can be improved.

  In addition, when the radial oil passage is formed in the pin boss portion, the concave groove is formed on the second side surface continuous with the pin boss portion, that is, the second side surface facing the swing direction of the upper link or the control link. According to the swinging motion of the control link, the concave groove is appropriately opened upward or downward. For this reason, the oil mist around the upper link, that is, the lubricating oil dripping from above or the lubricating oil splashed from below can be captured by the entire concave groove, and the collection efficiency of the lubricating oil can be increased. it can. Therefore, by supplying the lubricating oil collected in the concave groove to the bearing portion of the upper pin and the control link through the radial oil passage, sufficient lubricating oil can be supplied to the bearing portion. Lubrication performance can be improved.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. First, an outline of the multi-link type piston crank mechanism will be described. FIG. 1 is a configuration explanatory view showing a configuration example in which this multi-link type piston crank mechanism is configured as a variable compression ratio mechanism. This mechanism includes a multi-link type piston crank mechanism mainly composed of a lower link 4, an upper link 5 and a control link 10.

  The crankshaft 1 includes a plurality of journal portions 2 and a crankpin 3, and the journal portion 2 is rotatably supported by a main bearing of the cylinder block 18. The crank pin 3 is eccentric from the journal portion 2 by a predetermined amount, and a lower link 4 is rotatably connected thereto. The counterweight 15 extends from the crank web connecting the journal portion 2 and the crankpin 3 to the opposite side of the crankpin 3. The lower link 4 is configured to be divided into two members as will be described later, and the crank pin 3 is fitted to a crank pin bearing portion at a substantially center.

  The upper link 5 has a lower end side rotatably connected to one end of the lower link 4 by an upper pin 6 and an upper end side rotatably connected to a piston 8 by a piston pin 7. The piston 8 receives combustion pressure and reciprocates in the cylinder 19 of the cylinder block 18.

  The control link 10 that restricts the movement of the lower link 4 is connected to the other end of the lower link 4 by a control pin 11 so as to be rotatable, and the lower end side is a cylinder block that becomes a part of the engine body via the control shaft 12. The lower part of 18 is rotatably connected. Specifically, the control shaft 12 is rotatably supported by the engine body and has an eccentric cam portion 12a that is eccentric from the center of rotation, and the lower end portion of the control link 10 is rotatable on the eccentric cam portion 12a. Is fitted. The rotation position of the control shaft 12 is controlled by a compression ratio control actuator (not shown) that operates based on a control signal from an engine control unit (not shown). In this example, the center line m of the cylinder 19 is relatively offset to the opposite side of the control pin 11 with respect to the rotation center of the crankshaft 1.

  In the variable compression ratio mechanism using the multi-link type piston crank mechanism as described above, when the control shaft 12 is rotated by the compression ratio control actuator, the center position of the eccentric cam portion 12a, particularly the cylinder block 18 and the like. The relative position with respect to the engine body changes. Thereby, the rocking | fluctuation support position of the lower end of the control link 10 changes. When the swing support position of the control link 10 changes, the stroke of the piston 8 changes, and the position of the piston 8 at the piston top dead center (TDC) becomes higher or lower. This makes it possible to change the engine compression ratio.

  Next, configurations and operational effects of the embodiment in which the present invention is applied to the upper link 5 among the upper link 5 and the control link 11 will be listed with reference to the drawings. In addition, the same referential mark is attached | subjected to the same component and the overlapping description is abbreviate | omitted suitably.

  2 shows an upper link 5 ′ according to a comparative example, FIG. 3 shows an upper link 5 according to a first embodiment of the present invention, (A) is a perspective view of the upper link alone, and (B) is (A). It is a cross-sectional view along line BB. The upper link link 5 (5 ′) includes a first pin boss portion 21 for a cylindrical piston pin into which the piston pin 7 is rotatably inserted and fitted, and a cylindrical shape into which the upper pin 6 is rotatably inserted and fitted. A second pin boss portion 22 for the upper pin 6, and a rod portion 23 (23 ′) that is integrally connected to the outer periphery of the pin boss portions 21, 22 at both ends and connects the pin boss portions 21, 22, and Is integrally cast. The rod portion 23 includes a pair of first side surfaces 25 smoothly connected to both side surfaces 24 facing the crankshaft direction of the pin boss portions 21 and 22 and a pair of second side surfaces 27 smoothly connected to the outer peripheral surfaces of the pin boss portions 21 and 22. And have.

  As shown in FIGS. 2B and 3B, the lower link 4 has a bifurcated shape in which the upper pin bifurcated pin boss portion 42 holding the upper pin 6 sandwiches the second pin boss portion 22 of the upper link 5 from both sides. ing. Further, the upper pin 6 is fixed to the upper pin bifurcated pin boss portion 42 by press-fitting or the like, thereby eliminating the need for lubrication between the lower link 4 and the upper pin 6 and making the lower link 4 smaller and simpler. And improvements in durability and reliability. On the other hand, securing durability and lubrication performance by increasing the surface pressure of the bearing portion of the second pin boss portion 22 of the upper link 5 and the upper pin 6 is a major issue.

  [1] Therefore, in the first embodiment shown in FIGS. 3 and 4, the rod portion 23 is formed with a concave groove 28 extending in the longitudinal direction of the rod portion 23 in the center portion in the crankshaft direction of each second side surface 27. The cross section is H-shaped. A pair of ribs 30 are provided on both sides of the concave groove 28. The concave groove 28 has a substantially rectangular cross section in this embodiment, but is not limited thereto, and may have a circular arc shape or the like. On the other hand, the rod portion 23 ′ of the comparative example shown in FIG. 2 has a cross-sectional I shape in which a concave groove 29 extending in the longitudinal direction of the rod portion 23 is formed in the center portion of each first side surface 25. That is, the rod portion 23 ′ of the comparative example has a shape in which the concave groove 29 can be seen when viewed from the crankshaft direction (the x-axis direction in FIGS. 2B and 3B). The rod portion 23 in the example has such a shape that the concave groove 28 cannot be seen in the crankshaft direction view.

  As in the comparative example, when the concave groove 29 is formed on the pair of first side surfaces 25 that are continuous with the both side surfaces 24 of the pin boss portions 21 and 22, the concave groove 29 is always formed regardless of the swing position of the upper link 5. In contrast to the one that opens to the side, the concave groove 28 faces the pair of second side surfaces 27 that are continuous with the outer peripheral surface 26 of the pin boss portions 21, 22, that is, in the swing direction of the upper link 5. When the second side surface 27 is formed, the groove 28 opens upward or downward as appropriate according to the swinging motion of the upper link 5, so that the oil mist around the upper link 5, That is, the lubricating oil dripping from the upper side and the lubricating oil splashed from the lower side can be caught by the entire concave groove 28, and the collection efficiency of the lubricating oil can be increased. Accordingly, by supplying the collected oil to the bearing portion of the second pin boss portion 22 and the upper pin 6 using a radial oil passage 31 described later, sufficient lubricating oil is supplied to the upper pin bearing portion. The lubricating oil film can be formed and secured satisfactorily, and the lubricating performance can be improved.

  Further, in this embodiment, since the concave groove 28 is formed on the second side surface 27 continuous with the outer peripheral surface 26 of the pin boss portion 22, the concave groove 29 is formed on the first side surface 25 continuous with the both side surfaces 24 of the pin boss portion 22. Compared to the formed comparative example, the shape is excellent in rigidity with respect to the secondary moment of inertia Iy in the y-axis direction, that is, the crank rotation direction in FIGS. 2B and 3B. Therefore, the crank shaft thickness b of the rod portion 23 of the upper link 5 can be reduced as compared with the comparative example while ensuring the same rigidity as that of the comparative example with respect to the secondary moment of inertia Iy in the crank rotation direction. It becomes possible.

  For reference, if the dimensions of each part are shown in FIGS. 2 (B) and 3 (B), the cross-sectional secondary moment of the comparative example is expressed by the following equations (1) and (2), and the cross-section of this example The second moment is expressed by the following equations (3) and (4).

  [2] The second pin boss portion 22 of the upper link 5 is formed with a radial oil passage 31 that radially penetrates the outer periphery and the inner periphery that rotatably supports the upper pin 6. The groove 28 is connected. In the first embodiment shown in FIGS. 3 and 4, the rod-side groove 28 </ b> A is formed on the second side surface 27 of the rod portion 23 so that the groove 28 is connected to the radial oil passage 31. And a boss-side groove 28B formed on the outer peripheral surface of the pin boss portion 22, and the rod-side groove 28A and the radial oil passage 31 are connected by the boss-side groove 28B. Or you may connect the rod side ditch | groove 28A directly to the radial direction oil path 31, without providing the boss side ditch | groove 28B like 2nd Example shown in FIG.

  Thus, by connecting the concave groove 28 to the radial oil passage 31, the lubricating oil collected by the concave groove 28 is reliably supplied to the upper pin bearing portion via the radial oil passage 31 to secure an oil film. The necessary and sufficient amount of oil can be secured.

  In the example shown in FIG. 4, radial oil passages 31 are provided at two locations corresponding to the pair of concave grooves 28, and the pair of radial oil passages are provided on the inner peripheral surface of the pin boss portion 22 serving as a bearing surface. An inner circumferential groove 32 that connects the paths 31 is formed. However, in the case where a sufficient amount of lubricating oil can be secured even if the radial oil passage 31 is provided at one location, the radial oil passage 31 is formed only at one location as shown in FIG. 5 in order to ensure rigidity. You may do it.

  [3] In the third embodiment shown in FIG. 6, the radial oil passage 31 </ b> A has a nozzle shape that gradually decreases in diameter from the outer peripheral side to the inner peripheral side of the pin boss portion 22. When the passage cross-sectional area of the radial oil passage 31 is very small as compared to the concave groove 28, by adopting such a nozzle shape, a large contraction ratio between the concave groove 28 and the radial oil passage 31A is obtained. When the oil is supplied from the concave groove 28 to the radial oil passage 31A, the contracted flow is prevented from abruptly decreasing, and the inflow air containing a lot of oil mist is more smoothly and smoothly passed through the radial oil passage 31A. To the upper pin bearing portion.

  [4] In the fourth embodiment shown in FIG. 7, the concave groove 28 has a tapered portion 28 </ b> C that gradually becomes deeper toward the radial oil passage 31. By inclining the groove depth of the concave groove 28 (28C) by the tapered portion 28C in this way, the amount of oil flowing into the radial oil passage 31 is increased and the concave groove 28 to the radial oil passage 31 is increased. The oil inflow angle can be made shallow, and the supply amount of the lubricating oil to the radial oil passage 31 can be increased.

  [5] In the fifth embodiment shown in FIG. 8, the concave portion 28 is formed on the outer periphery of the pin boss portion 22, and the concave groove extending portion 28 </ b> D extending from the radial oil passage 31 to the opposite side / back side of the rod portion 23. Have. In this way, by providing the recessed groove extension 28D also on the back side of the radial oil passage 31, as shown by the arrow Y1 in the figure, the lubricating oil or the like splashed from the lower side of the upper link 5 is transferred to the recessed groove. It can be captured by the extension portion 28D and supplied to the radial oil passage 31 side, and the collection property of the lubricating oil can be further enhanced.

  [6] FIGS. 9B and 9C are cross-sectional views corresponding to the BB cross section of FIG. 9A. As shown in FIGS. 9A and 9B, when a concave groove extending portion 28D (boss side concave groove 28B), which is a part of the concave groove 28, is formed on the outer periphery of the pin boss portion 22 of the upper link 5, the pin boss Both end portions 33 in the axial direction of the portion 22 are relatively thick in the axial direction to increase rigidity, and the contact load from the upper pin 6 tends to concentrate in the region R1 of the both end portions 33 in the axial direction.

  Here, as shown in FIG. 3B, the lower link 4 is provided with a bifurcated upper pin bifurcated pin boss portion 42 sandwiching the pin boss portion 22 from both sides, and the upper pin 6 is connected to the upper pin bifurcated pin boss portion 42. Both ends are fixed by press-fitting. As shown in FIG. 9C, the upper pin 6 inserted and fitted into the pin boss portion 22 of the upper link 5 is fixed by the press-fit structure in which both ends of the upper pin 6 are fixed to the bifurcated pin boss portion 42 of the lower link 4. The central portion has a barrel shape or barrel shape in which the center swells thicker than both axial ends, and the above-described concentration of the contact load at both axial ends can be reduced. Note that in FIG. 9C, the curve is exaggerated for the sake of explanation.

  [7] FIG. 10 is a top view (A) and a front view (B) showing the lower link 4 according to the sixth embodiment alone. The lower link 4 includes a crank pin bearing portion 41 at the substantially center where the crank pin 3 is fitted, a bifurcated upper pin bifurcated pin boss portion 42 for holding the upper pin 6, and the other end portion for holding the control pin 11. The control pin bifurcated pin boss portion 43 is provided. For assembly to the crankpin 3, a lower link upper 45 including an upper pin bifurcated pin boss portion 42 and a control pin bifurcated pin boss portion 43 along a split surface 44 passing through the center of the crankpin bearing portion 41. And the lower link lower 46 including the two, and both 45 and 46 are integrally fastened by two bolts 47 and 47A respectively disposed on both sides of the crankpin bearing portion 41. Assuming that the cylinder 19 is arranged in the vertical direction, the lower link upper 45 is positioned on the upper side and the lower link lower 46 is positioned on the lower side in the crankcase.

  The upper pin bifurcated pin boss portion 42 has a bifurcated shape sandwiching the pin boss portion 22 of the upper link 5, and both axial ends of the upper pin 6 are fixed by press-fitting. That is, the pin boss portion 22 of the upper link 5 is rotatably combined with the inner side of the bifurcated pin boss portion 42 of the lower link 4. Similarly, the bifurcated pin boss portion 43 for the control pin in the control pin 11 is formed in a bifurcated shape, and a pin boss portion 11A (see FIG. 1) at one end of the control link 10 is rotatably combined inside the bifurcated portion. .

  The lower link 4 is provided with a pair of ribs 48 connected to the bifurcated pin boss portions 42 and 43, and when the lower link 4 is viewed from the side ((B) of FIG. 10), An outer peripheral convex portion 52 having a convex shape toward the side of the link 4 is provided over substantially the entire periphery of the lower link 4. The load applied to the lower link is transmitted via the outer peripheral convex portion 52 (the outer peripheral convex portion 52 bears correspondingly). An interference avoiding groove 49 for avoiding interference with the swinging upper link 5 is formed between the pair of ribs 48.

  Here, as described above, since the thickness b (see FIG. 3) of the upper link 5 in the crankshaft direction is set to be thin, the groove width D2 of the interference avoidance groove 49 is between the bifurcated pin boss portions 42. It is set smaller than the gap D1. For this reason, the ribs 48 on both sides of the interference avoiding groove 49 are partially thickened. As the rib 48 is thus thickened, the rigidity in the rotational direction around the crank pin of the lower link 4 can be increased.

  [8] Further, concave portions 50 are formed on both side surfaces of the lower link 4 mainly for weight reduction. The concave portion 50 is recessed in the radial direction from the bearing portion 41 and the pin boss portions 42 and 43, and the outer peripheral convex portion 52 of the lower link 4 provided on the pair of ribs 48 and the crankpin bearing portion 41. And the periphery of the crankpin bearing portion 41. And the recessed part 50 is locally deeply set by the part 50A corresponding to the interference avoidance groove | channel 49 mentioned above. In the vicinity of the interference avoidance groove 49, the rib 48 is thickened as described above, and since the thickened rib 48 is close to the crankpin bearing portion 41, the circumferential direction of the crankpin bearing portion 41 is increased. Among them, the local rigidity tends to be high. Therefore, by setting the recess 50A deeply in this way, the rigidity of the crankpin bearing portion 41 in the vicinity of the interference avoiding groove 49 is reduced, and for example, a bearing that is caused by uneven distribution of rigidity in the circumferential direction of the crankpin bearing portion 41. It is possible to suppress the contact between the pin and the pin and improve the lubrication performance.

  [9] Referring to FIG. 11, in the pin boss portion 22, the portion connecting / intersecting with the rod portion 23, i.e., the extension portion R <b> 2 on the extension of the rod portion 23, causes a combustion load or the like from the rod portion 23. If a radial oil passage is provided in the extended portion R2 because a large load is input, it is difficult to ensure the strength and rigidity of the pin boss portion 22. Therefore, in the seventh embodiment shown in FIG. 11, the radial oil passage 31 </ b> B is provided at a position away from the extended portion R <b> 2 of the rod portion 23 in the pin boss portion 22. That is, the strength / rigidity of the pin boss portion 22 is increased by providing the radial oil passage 31B while avoiding the extended portion R2 on which a large load acts. Further, by connecting the concave groove 28 to the radial oil passage 31 by the boss side concave groove 28B, the lubricating oil caught by the concave groove 28 can be satisfactorily supplied to the radial oil passage 31B. A sufficient amount of oil can be secured.

  [10] Referring to FIG. 12, in the pin boss portion 22, the region R <b> 3 near the rod portion 23, i.e., the region R <b> 3 on the upper link upper side which is vertically upward in the vehicle-mounted state, For example, if a radial oil passage is provided in the region R3 because a large load such as the above is input, it is difficult to ensure the strength and rigidity of the pin boss portion 22. Therefore, in the eighth embodiment shown in FIG. 12, the radial oil passage 31C is provided in the region R4 of the pin boss portion 22 opposite to the rod portion 23, that is, the region R4 on the lower side of the upper link. By providing the radial oil passage 31C while avoiding the region R3 near the rod portion 23 where a large load acts in this way, the strength and rigidity of the pin boss portion 22 can be improved, and the boss side concave groove 28B By connecting the concave groove 28 to the radial oil passage 31C, the lubricating oil caught by the concave groove 28 can be satisfactorily supplied to the radial oil passage 31C, and a sufficient amount of oil is supplied to the upper pin bearing portion. be able to.

  [11] In the ninth embodiment shown in FIG. 13, of the pair of concave grooves 28 of the upper link 5, the concave groove 28E near at least the lower link 4 (the side swinging so as to approach the lower link 4) is in the radial direction. It is connected to the oil passage 31. A splash hole 51 for injecting and supplying lubricating oil is formed in the lower link 4. One end of the splash hole 51 opens in the inner periphery of the crankpin bearing portion 41, and the other end 51A opens in the bottom surface 49A of the interference avoiding groove 49 facing the upper link 5 (see FIG. 10). Lubricating oil supplied to the bearing portion 41 is injected and supplied from the other end 51A. The other end 51 </ b> A of the splash hole 51 is formed at a position facing the groove 28 </ b> E on the lower link side of the upper link 5.

  As a result, the lubricating oil ejected through the splash hole 51 can be collected by the lower link-side concave groove 28E in the upper link 5 and supplied to the lubricating portion with the upper pin 6 through the radial oil passage 31. Further, the lubrication performance can be further improved.

  [12] Further, the splash hole 51 is inclined toward the radial oil passage 31 with respect to the radial direction 41 </ b> A of the crankpin bearing portion 41. As a result, the injection direction from the splash hole 51 becomes closer to the radial oil passage 31, and the inflow angle with respect to the concave groove 28E becomes shallow, so that the collection efficiency of the lubricating oil is improved and lubrication to the upper pin bearing portion is performed. The amount of oil can be increased effectively.

  [13] As described above, in each of the above-described embodiments, the rod portion 23 having the H-shaped section is provided on the pin boss portion 22 for the upper pin 6 in the upper link 5, so that the bearing portion of the upper pin 6 in which it is difficult to ensure the lubricating performance. It is possible to improve the rigidity of the lower link 4 and the bearing performance of the crankpin bearing portion by reducing the axial thickness of the upper link 5 while greatly improving the lubrication performance.

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, by providing the pin boss portion 11A for the control pin 11 in the control link 10 with the rod portion having the H-shaped section as described above, it is possible to obtain the same effects as the above-described embodiments. Some of the above embodiments may be combined.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows an example of the multiple link type piston crank mechanism of the internal combustion engine which concerns on this invention. The upper link which concerns on a comparative example is shown, (A) is a perspective view, (B) is a BB cross-section corresponding view of (A). The upper link which concerns on 1st Example of this invention is shown, (A) is a perspective view, (B) is a BB cross-section corresponding view of (A). The perspective view which shows the vicinity of the pin boss | hub part for upper pins in the upper pin of the said 1st Example. Sectional drawing which shows the vicinity of the pin boss | hub part for upper pins in the upper pin which concerns on 2nd Example of this invention. Sectional drawing which shows the vicinity of the pin boss | hub part for upper pins in the upper pin which concerns on 3rd Example of this invention. Sectional drawing which shows the vicinity of the pin boss | hub part for upper pins in the upper pin which concerns on 4th Example of this invention. Sectional drawing which shows the vicinity of the pin boss | hub part for upper pins in the upper pin which concerns on 5th Example of this invention. (A) is sectional drawing of an upper pin, (B) And (C) is a BB cross-section corresponding figure of (A). The top view (A) and front view (B) which show the lower link based on 6th Example of this invention alone. Sectional drawing which shows the vicinity of the pin boss | hub part for upper pins in the upper pin which concerns on 7th Example of this invention. Sectional drawing which shows the vicinity of the pin boss | hub part for upper pins in the upper pin which concerns on 8th Example of this invention. Sectional corresponding drawing which shows the upper link and lower link which concern on 9th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Crankshaft 3 ... Crankpin 4 ... Lower link 5 ... Upper link 7 ... Piston pin 8 ... Piston 10 ... Control pin 11 ... Control link 22 ... Pin boss part 23 ... Rod part 24 ... Side surface of pin boss part 25 ... First side surface 26 ... Outer peripheral surface of pin boss part 27 ... Second side surface 28 ... Concave groove 31 ... Radial oil passage

Claims (13)

An upper link having one end connected to the piston via a piston pin, a lower link connected to the other end of the upper link via an upper pin, and connected to the crank pin of the crankshaft, and one end on the engine body side In a multi-link type piston crank mechanism of an internal combustion engine comprising: a control link supported so as to be swingable and having the other end connected to the lower link via a control pin;
At least one of the upper link and the control link has a cylindrical pin boss portion into which the upper pin or the control pin is rotatably fitted, and a rod portion integrally connected to the pin boss portion,
The rod portion has a pair of first side surfaces that are continuous with the side surfaces of the pin boss portion, and a pair of second side surfaces that are continuous with the outer peripheral surface of the pin boss portion. It has a cross-sectional H shape in which an extending groove is formed ,
And a multi-link type internal combustion engine having a radial oil passage that penetrates the inner periphery and the outer periphery of the pin boss portion in the radial direction, and the radial oil passage is connected to the concave groove. Piston crank mechanism. 2. The multi-link piston crank mechanism for an internal combustion engine according to claim 1 , wherein the radial oil passage has a nozzle shape that gradually decreases from an outer peripheral side to an inner peripheral side of the pin boss portion. . The multi-link piston crank mechanism for an internal combustion engine according to claim 1 or 2 , wherein the concave groove has a tapered portion that gradually becomes deeper toward the radial oil passage. The recess is formed on the outer periphery of the pin boss portions, any one of claims 1 to 3, characterized in that it has a groove extension extending to the opposite side of the rod part than the radial oil passage A double-link type piston crank mechanism for an internal combustion engine according to claim 1. The above lower link, bifurcated pin boss portion is provided which forms a bifurcated sandwiching the pin boss portion, one of the claims 1 to 4, both ends of the upper pin or control pin to the bifurcated pin boss portion is characterized in that it is fixed A multi-link type piston crank mechanism for an internal combustion engine according to claim 1. A pair of ribs connected to the bifurcated pin boss portion are provided on the outer peripheral edge of the lower link, and an interference avoiding groove for avoiding interference with the upper link or the control link is formed between the pair of ribs. 6. The multi-link type piston crank mechanism for an internal combustion engine according to claim 5 , wherein a groove width of the interference avoiding groove is smaller than a gap between the bifurcated pin boss portions. The lower link has a crankpin bearing portion into which the crankpin is rotatably fitted, and concave portions are provided on both side surfaces of the lower link,
The multi-link type piston crank mechanism for an internal combustion engine according to claim 6 , wherein the recess is deeply set at a portion corresponding to the interference avoiding groove. The multi-link type piston crank mechanism for an internal combustion engine according to any one of claims 1 to 7 , wherein the radial oil passage is provided at a position away from an extended portion of the rod portion in the pin boss portion. . The multi-link type piston crank mechanism for an internal combustion engine according to any one of claims 1 to 8 , wherein the radial oil passage is provided in a region of the pin boss portion opposite to the rod portion. Of the pair of concave grooves, the radial oil passage is connected to a concave groove near at least the lower link,
The internal combustion engine according to any one of claims 1 to 9 , wherein a splash hole for supplying lubricating oil to the lower link is formed at a position facing the concave groove on the lower link side. Double link type piston crank mechanism. A crankpin bearing portion that rotatably supports the crankpin is provided on the lower link,
The multi-link type piston crank mechanism for an internal combustion engine according to claim 10 , wherein the splash hole is inclined closer to the radial oil passage with respect to a radial direction of the crank pin bearing portion. The multi-link type piston crank mechanism for an internal combustion engine according to any one of claims 1 to 11 , wherein the upper link is provided with a rod portion having an H-shaped cross section. The internal combustion engine according to any one of claims 1 to 12 , wherein the double link type piston crank mechanism constitutes a variable compression ratio mechanism by changing a swing fulcrum position of the control link on the engine body side. Double link type piston crank mechanism of the engine.

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